Congressional Careers: Service Tenure and Patterns of Member Service, 1789-2023

Congressional Careers: Service Tenure and
January 17, 2023
Patterns of Member Service, 1789-2023
Sarah J. Eckman
The average service tenure of Members of the Senate and House of Representatives has varied
Analyst in American
substantially since 1789. This report presents data on Member tenure over time, analyzes factors
National Government
that affect average tenure in any given Congress, and examines historical patterns of

congressional service, including the distribution of years served in each Congress, and the cross-
Amber Hope Wilhelm
chamber experience of Representatives and Senators.
Visual Information
Specialist
During much of the 19th century, the average tenure of Representatives and Senators remained

relatively steady, with incoming Representatives generally averaging between two and three
years of prior service in most Congresses, and the Senators averaging between three and five

years. Beginning in the late 19th and through much of the 20th century, average tenure for
Members in both chambers steadily increased. Senators’ average years of prior service has increased from just under five
years during the early 1880s to approximately 10 years in the most recent Congress. Similarly, the average tenure of
Representatives has increased from approximately three years during the early 1880s to approximately nine years in the most
recent Congress.
The average years of service for Members elected to the 118th Congress, as of January 3, 2023, when the Congress convened,
was 8.5 years for the House and 11.2 years for the Senate. In comparison, the average years of service for Members elected to
the 117th Congress, as of January 3, 2021, when the Congress convened, was 8.9 years for the House and 11.1 years for the
Senate.
This report analyzes two factors that influence variation over time in the average years of service for Members of Congress:
the decision of sitting Members whether or not to seek election to the next Congress, and the success rate of Members who
do seek reelection. Observed increases in the proportion of Members seeking reelection and decreases in the proportion of
Members defeated for reelection align with previous scholarly assessments of congressional history, which conclude that
during the early history of Congress, turnover in membership was frequent and resignations were commonplace, and that
during the 20th century, congressional careers lengthened as turnover decreased and Congress became more professionalized.
The report also examines two further issues related to Member tenure, including the distribution of Member service over
time, as well as Members’ cross-chamber experience. Although the average service tenure of Members has increased since
Congress’s early years, a substantial portion of Representatives and Senators in recent Congresses have served for six years
or less in their respective chambers. With respect to cross-chamber experience, while a small proportion of Representatives
historically have had previous Senate experience, a sizable percentage of Senators throughout congressional history have had
previous House experience.
Congressional Research Service


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Contents
Introduction ..................................................................................................................................... 1
Methodology ................................................................................................................................... 1

Data ........................................................................................................................................... 1
Average Service Tenure ................................................................................................................... 2
House of Representatives .......................................................................................................... 3
Senate ........................................................................................................................................ 4
Factors Affecting Average Tenure ............................................................................................. 4

The Rate of Members Seeking Reelection .......................................................................... 4
Reelection Success Rate ..................................................................................................... 5
Discussion ........................................................................................................................... 6
Patterns of Congressional Service ................................................................................................... 8
Distribution of Service Experience ........................................................................................... 8
House of Representatives .................................................................................................... 8
Senate .................................................................................................................................. 8

Cross-Chamber Experience ..................................................................................................... 12
Senators with Prior House Experience.............................................................................. 12
Representatives with Prior Senate Experience .................................................................. 12
Amount of Cross-Chamber Experience ............................................................................ 13
Concluding Observations .............................................................................................................. 13

Figures
Figure 1. Average Years of Prior Service in Chamber, Senators and Representatives .................... 3
Figure 3. Percentage of Representatives Who Did Not Seek Reelection ........................................ 5
Figure 4. Percentage of Representatives Defeated for Reelection .................................................. 6
Figure 5. Distribution of Member Tenure, House of Representatives ........................................... 10
Figure 6. Distribution of Member Tenure, Senate .......................................................................... 11
Figure 7. Percentage of Members with Cross-Chamber Experience ............................................. 12
Figure 8. Average Years of House Service Among Senators ......................................................... 13

Contacts
Author Information ........................................................................................................................ 14


Congressional Research Service


Congressional Careers: Service Tenure and Patterns of Member Service, 1789-2023

Introduction
This report presents data on average Member tenure over time, analyzes several factors that affect
tenure in any given Congress, and examines historical patterns of congressional service, including
the distribution of years served within each Congress, and the cross-chamber experience of
Representatives and Senators.
During much of the 19th century, the average tenure of Representatives and Senators remained
relatively steady, with incoming Representatives generally averaging between two and three years
of prior service in most Congresses, and Senators averaging between three and five years.
Beginning in the late 19th and through much of the 20th century, average tenure for Members in
both chambers steadily increased. The average years of service for Members elected to the 118th
Congress, as of January 3, 2023, when the Congress convened, was 8.5 years for the House and
11.2 years for the Senate.
Two factors that affect average years of service are examined in this report: the percentage of
Members choosing to seek reelection, and the success rate of Members who do seek reelection.
The findings presented here align with scholarly assessments of congressional history, which
conclude that during the early history of Congress, turnover in membership was frequent and
resignations were commonplace. Many lawmakers in the 18th and early 19th centuries might be
characterized as “citizen legislators,” holding full-time nonpolitical employment and serving in
Congress on a part-time basis for a short number of years. During the 20th century, congressional
careers lengthened as turnover decreased and Congress became more professionalized.
The report also examines two further issues related to Member tenure, including the distribution
of Member service over time, as well as Members’ cross-chamber experience. Although the
average tenure of Members has increased since the late 19th century, a substantial portion of
Representatives and Senators in recent Congresses have served for six years or less in their
respective chambers. With respect to cross-chamber experience, while a small proportion of
Representatives have historically had previous Senate experience, a sizable percentage of
Senators throughout congressional history have had previous House experience.
Methodology
Data
Data on the tenure of Members of Congress for the 1st through 115th Congresses are drawn from
the Biographical Directory of the United States Congress,1 which records each Member’s service
in the House and Senate from the 1st Congress through the present. Specifically, each Member
listed in the Biographical Directory was recorded, along with the beginning and ending dates of
the Congresses in which the directory indicates they served. To identify any instances where a
Member did not serve for the entire duration of a particular Congress, individual Member
biographies contained in the Biographical Directory were consulted, in addition to the Roster of
United States Congressional Officeholders and Biographical Characteristics of the United States


1 See Biographical Directory of the United States Congress, at http://bioguide.congress.gov/biosearch/biosearch.asp
(accessed December 17, 2018).
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Congress, 1789-1996,2 as well as the Congressional Directory3 for evidence that a Member’s
service began after the opening day of a Congress, or ended prior to the last day of a Congress.
Data for new Members of the 116th-118th Congresses come from the Clerk of the House and CQ
Press publications.4 Each Member’s service in a given Congress in years is calculated by dividing
their total days served in that Congress by 365.25. As of the beginning date of each Congress,
each Member’s years of total prior service in each chamber is calculated.
Data on Member tenure as described above are aggregated to generate a series of summary
statistics for each chamber from the 1st through 118th Congresses. Statistics are calculated as of
the first day of the Congress. For example, the average tenure of Senators in the 116th Congress is
generated by first identifying those Senators who served during the opening day of the Congress
(January 3, 2019), obtaining each Senator’s total years of prior service in the Chamber as of the
opening day of the Congress, and computing the average for the chamber.5 Consequently, any
changes in membership during the term arising from vacancies and replacements are not taken
into account. In addition, the statistics reported on average tenure over time include prior service
within the chamber, but do not include cross-chamber experience (i.e., years of Senators’ House
experience, or Representatives’ Senate experience). Freshman Members in each chamber are
considered to have zero years of prior chamber service.
Average Service Tenure
As shown in Figure 1 below, the average years of service of Members in both chambers has
generally increased over time. The prior House service of incoming Representatives increased
from an average of 2.5 years in the 19th century to 9.4 in the 21st to date; the average peaked at
10.3 years—just over five terms—during the 102nd (1991-1992), 110th (2007-2008), and 111th
Congresses (2009-2010). Incoming Senators averaged 4.8 years of prior chamber service in the
19th century, and 11.2 years during the 21st century to date. This figure peaked at 13.1 years
during the 111th Congress (2009-2010).
For both the House and Senate, the Congress with the fewest average years of prior experience
was the 1st, as all Senators and Representatives necessarily had zero years of experience upon
arrival. In the last 50 years, the Congress with the lowest average years of service among
Representatives and Senators was the 97th Congress (1981-1982), in which incoming
Representatives had an average of 7.4 years of prior service in the House (slightly more than 3.5
terms) and Senators had an average of 7.5 years of prior service in the Senate (1.25 terms).

2 Inter-university Consortium for Political and Social Research, and Carroll McKibbin. Roster of United States
Congressional Officeholders and Biographical Characteristics of Members of the United States Congress, 1789-1996:
Merged Data
[computer file] 10th ICPSR ed. (Ann Arbor: MI: Inter-university for Political and Social Research
[producer and distributor], 1997).
3 Official Congressional Directory, 105th-115th Congress; available at https://www.gpo.gov/fdsys/browse/
collection.action?collectionCode=CDIR (accessed December 21, 2020).
4 CQ Roll Call, Guide to the New Congress, 116th Congress, November 12, 2018; and CQ Roll Call, Guide to the 117th
Congress
, December 9, 2020.
5 For a variety of reasons (including deaths, resignations, and contested elections, among others), less than a full
complement of Representatives and Senators were sworn in on the first day of a new Congress on a number of
occasions throughout history. Consequently, statistics contained in this report may be calculated based on less than the
full membership of each chamber if any vacancies existed on the opening day of the Congress. Members of the House
of Representatives for the 118th Congress were sworn in on the legislative day of January 6, 2023 (though early in the
next calendar day of January 7). For consistency of the data, calculations around Member service for the 118th
Congress are dated to January 3, the date the 118th Congress convened.
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Figure 1. Average Years of Prior Service in Chamber, Senators and Representatives
1st through 118th Congresses

Sources: CRS analysis of Biographical Directory of the United States Congress, ICPSR, and proprietary data. Inter-
university Consortium for Political and Social Research, and Carrol McKibbin, Roster of United States
Congressional Officeholders and Biographical Characteristics of Members of the United States Congress, 1789-1996:
Merged Data
[computer file] 10th ICPSR ed. (Ann Arbor: MI: Inter-university Consortium for Political and Social
Research [producer and distributor], 1997).
House of Representatives
As shown in Figure 1, during the 19th century (7th through 56th Congresses), the average service
of Representatives remained relatively steady; during this time incoming Representatives
averaged between 1.4 and 3.8 years of prior service.6 Around the turn of the 20th century, the
average began to increase, rising from just over four years at the beginning of the century, to
approximately nine years in each of the three most recent prior Congresses. At the start of the
118th Congress, the average years of prior service for Representatives was 8.5 years.
Among Members serving in the 118th Congress, Representatives Harold Rogers and Christopher
Smith are the longest-serving Representatives, with approximately 42 years of service in the
House as of the beginning of the Congress.7

6 Data on service tenures of the earliest Congresses are purposely omitted from this discussion. Average service tenure
in the 18th century Congresses (1st through 6th) is artificially constrained by the inability of anyone to have begun his
service prior to the 1st Congress. While this artificial constraint is theoretically active well into the early 19th century
(for example, no Member of the 11th Congress could have had more than 20 years of prior service), it is a practical
analytical constraint only for the first five or seven Congresses. After that, aggregate service tenures stabilize in line
with observed trends during the remainder of the first half of the 19th century. Furthermore, average tenure decreases in
the House in the fifth and eighth Congresses and in the seventh and ninth Senates, which indicates that while the
artificial constraint may be theoretically suppressing the aggregate service average, it is no longer a dominant practical
factor.
7 These two Members have served the same number of days in the House. Rep. Harold Rogers is the dean of the House,
however, and is considered the Member with the most seniority at the start of the 118th Congress.
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Senate
Historically, the average years of service among Senators has been similar to that of
Representatives, with relative stability during much of the 19th century, followed by a steady
increase beginning in the late 19th and early 20th century. As shown in Figure 1, for much of the
19th century, the average prior service of Senators remained roughly constant at approximately
four years. Beginning in the 1880s, the average began to rise steadily, predating the similar rise in
the House by about 20 years. After falling dramatically for a short time in the 1910s, the average
years of prior service in the Senate began to rise steadily again, tracking the rise in average years
of service among Representatives. At the start of the 118th Congress, incoming Senators averaged
11.2 years of prior Senate service.
Among Members serving in the 118th Congress, the longest-serving Senator is Chuck Grassley,
with 42 years of service in the Senate as of the beginning of the 118th Congress.
Factors Affecting Average Tenure
Among the many factors that may affect variation in Member seniority over time, two are
examined in this report: the decision of sitting Members whether or not to seek reelection to the
next Congress, and the success rate of Members who do seek reelection.8 Each of these
components is discussed below in greater detail.
The Rate of Members Seeking Reelection
The average years of prior service for Representatives and Senators is influenced by Member
choices about whether or not to seek reelection to the chamber. If a large number of Members in
one Congress choose not to seek reelection, many Members of the subsequent Congress will
necessarily be first-term Members with no prior service. Members might not seek reelection for
any number of reasons; common historical reasons include seeking another office, appointment to
other government positions, retirement from public service, and death.
Figure 2 plots the percentage of Representatives in each Congress who did not seek reelection to
the following Congress.9

8 Short-term changes in average service can also be affected by the departure of a relatively small number of long-
serving Members. For example, Senators Robert Byrd and Edward Kennedy both passed away during the 111th
Congress and had Senate service of 50 and 46.2 years, respectively. This helps explain, in part, the decline in average
service tenure in the Senate between the 111th and 112th Congresses.
9 Senators are excluded from this analysis due to the difficulty in definitively assessing whether Senators sought
reelection prior to the enactment of the 17th amendment, which provided for direct Senate elections.
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Figure 2. Percentage of Representatives Who Did Not Seek Reelection
1st through 117th Congresses

Sources: CRS analysis of Biographical Directory of the United States Congress, ICPSR, and proprietary data. Inter-
university Consortium for Political and Social Research, and Carrol McKibbin, Roster of United States
Congressional Officeholders and Biographical Characteristics of Members of the United States Congress, 1789-1996:
Merged Data
[computer file] 10th ICPSR ed. (Ann Arbor: MI: Inter-university Consortium for Political and Social
Research [producer and distributor], 1997).
Notes: Opening year of each Congress is noted in parentheses.
As shown in Figure 2, the rate of Representatives not seeking reelection dropped dramatically
beginning in the mid-19th century. Prior to the 1860s, it was common for 40% of Representatives
or more not to seek reelection, and prior to the 46th Congress (1879-1880) this figure never fell
below 25%. After declining in the latter part of the 19th century, the rate at which Members have
not sought reelection has remained relatively steady during the 20th and 21st centuries, averaging
approximately 11.6% during this time period.
Reelection Success Rate
In addition to the rate at which Members seek reelection, a second important factor in
understanding variation in average seniority in Congress is the success rate among Members who
do seek reelection.10 Figure 3 plots the percentage of Representatives in each Congress who
sought reelection to the next Congress but were defeated, either in their attempt to gain their
party’s nomination or in the general election for office.11

10 Note that the two variables—Member decisions to seek reelection and whether or not the Member is defeated for
reelection—are tied to one another; the decision to seek reelection may be based, in part, on an estimate of the
likelihood of success. Accordingly, a decrease in the percentage of Members who are defeated for reelection may be
indicative of greater trends, but in some cases may reflect an increase in Members choosing not to stand for reelection
when their reelection prospects are diminished.
11 Senators are again excluded due to the difficulty in assessing Senate elections prior to the 17th amendment.
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Figure 3. Percentage of Representatives Defeated for Reelection
1st through 117th Congresses

Sources: CRS analysis of Biographical Directory of the United States Congress, ICPSR, and proprietary data. Inter-
university Consortium for Political and Social Research, and Carrol McKibbin, Roster of United States
Congressional Officeholders and Biographical Characteristics of Members of the United States Congress, 1789-1996:
Merged Data
[computer file] 10th ICPSR ed. (Ann Arbor: MI: Inter-university Consortium for Political and Social
Research [producer and distributor], 1997).
As shown in Figure 3, the percentage of Representatives defeated for reelection generally
increased during the 19th century, and later declined over the course of the 20th century. There was
significant short-term variation resulting from high-turnover elections, including the 1872, 1890,
1894, and 1932 elections (to the 43rd, 52nd, 54th, and 72nd Congresses, respectively).
Discussion
The data presented in Figure 2 and Figure 3 align with scholarly assessments of congressional
history, which conclude that during the early history of Congress, turnover in membership was
frequent and resignations were commonplace, and that during the 20th century, congressional
careers lengthened as turnover decreased and Congress became more professionalized.
Many lawmakers in the 18th and early 19th centuries might be characterized as “citizen
legislators,” holding full-time nonpolitical employment and serving in Congress on a part-time
basis for a short number of years. According to political scientist Randall Ripley, “In the pre-
modern Congress, Members came and went rapidly. There were few senior Members. Life in
Washington was not pleasant; Congress did not seem very important.”12
According to H. Douglas Price, the lack of incentives for Members to retain their seats explains
the high turnover in those early years of the House. Power was fluid in the House. The Speaker

12 Randall B. Ripley, Congress: Process and Policy, 4th ed. (New York: W.W. Norton and Company, 1988), p. 50. See
also H. Douglas Price, who wrote that “the distinguished Senators of the 1st Congress set the early career pattern for
that chamber: They fled the Capitol ... almost as fast as humanly possible.... Career data on the early Senate is a morass
of resignations, short-term appointees, elective replacements.... There are no notable careers in terms of service.” H.
Douglas Price, “Congress and the Evolution of Legislative ‘Professionalism,’” in Norman Ornstein, ed., Congress in
Change
(New York: Praeger Publishers, 1995), p. 5.
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controlled committee appointments, changes in party control were common, and seniority in the
chamber was not yet as valuable as it would later become.13
After the Civil War, circumstances changed and precipitated a rise of careerism in Congress.14
Legislative careers became professionalized, and the concept of the “citizen legislator” became a
thing of the past.15 Some observers attribute this to institutional changes in the structure of
congressional elections, such as the strengthening of the party system and the emergence of one-
party states and districts following the Civil War.16 Others have identified redistricting practices
as a potential factor in lengthening careers.17 Recent scholarship has pointed to historical electoral
reforms, such as adoption of the secret ballot and nominating primaries, as contributing to the
increases in average tenure around the turn of the 20th century.18
Other scholars have pointed to institutional changes in congressional operations, such as the rise
of the seniority system, the development of the committee system, and new advantages of
incumbency that allowed Members to generate publicity, serve constituents, and receive support
in organizing their offices and forming agendas that help them be effective legislators.19 In
addition, the development of transportation technology made travel between Washington and a
Member’s home district less burdensome, potentially increasing the attractiveness of a longer
career.
Finally, the emergence of national problems raised a legislative career to a new level of
importance. As the federal government took on new responsibilities, both after the Civil War and
in the early 20th century, Members may have begun to view congressional office as relatively
more desirable than state office, and this may have contributed to many Members’ desire to

13 Ibid., p. 16.
14 David Brady, Kara Buckley, and Douglas Rivers, “The Roots of Careerism in the House of Representatives,”
Legislative Studies Quarterly, vol. 24, no. 4 (November 1999), p. 490.
15 John R. Hibbing, “The Modern Congressional Career,” The American Political Science Review, vol. 85 (June 1991),
pp. 404-425; Howard Baker, “‘Citizen Legislators’ Would Be Better,” Washington Post, July 8, 1983, p. 21; and Saul
Pett, “Baker Seeks to Change Face of Congress,” Los Angeles Times, August 21, 1983, pp. 2, 15.
16 Robert G. Brookshire and Dean F. Duncan, “Congressional Career Patterns and Party Systems,” Legislative Studies
Quarterly
, vol. 8, no. 1 (February 1983), pp. 65-78; Nelson Polsby, “The Institutionalization of the U.S. House of
Representatives,” The American Political Science Review, vol. 41, no. 1 (March 1968).
17 Seth C. Mckee, “The Effects of Redistricting on Voting Behavior in Incumbent U.S. House Elections, 1992-1994,”
Political Research Quarterly, vol. 61, no. 1 (March 2008), pp. 122-133; Jamie L. Carson, Erik J. Engstrom, and Jason
M. Roberts, “Redistricting, Candidate Entry, and the Politics of Nineteenth-Century U.S. House Elections,” American
Journal of Political Science
, vol. 50, no. 2 (April 2006), pp. 283-293.
18 Jamie L. Carson and Jason M. Roberts, Ambition, Competition, and Electoral Reform: The Politics of Congressional
Elections Across Time
(Ann Arbor: University of Michigan Press, 2013); Erik J. Engstrom and Samuel Kernell, Party
Ballots, Reform, and the Transformation of America’s Electoral System
(New York: Cambridge University Press,
2014); Scott A. MacKenzie, “Life Before Congress: Using Pre-Congressional Experience to Assess Competing
Explanations for Political Professionalism,” Journal of Politics, vol. 77, no. 2 (April 2015), pp. 505-518.
19 On the seniority system, see Polsby, “The Institutionalization of the U.S. House Representatives”; Michael Abram
and Joseph Cooper, “The Rise of Seniority in the House of Representatives,” Polity, vol. 1, no. 1 (August 1968), pp.
52-85; on the development of the committee system, see Walter Kravitz, “Evolution of the Senate’s Committee
System,” Annals of the American Academy of Political Science, vol. 411 (January 1974), pp. 27-38; George B.
Galloway, “Development of the Committee System in the House,” The American Historical Review, vol. 65, no. 1
(October 1959), pp. 17-30; on the development of Member resources, see Richard Fenno, Homestyle: House Members
and Their Districts
(Boston: Little, Brown, 1978); Bruce Cain, John Ferejohn, and Morris Fiorina, The Personal Vote:
Constituency Service and Electoral Independence
(Cambridge, MA: Harvard University Press, 1987).
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remain in Congress.20 During the 117th Congress, eight House Members sought state office and
one House Member sought local office instead of seeking reelection to the 118th Congress.
Patterns of Congressional Service
Distribution of Service Experience
Examining the aggregate average years of Member service in a given Congress reveals little
about the underlying distribution of service among individual Members. Figure 4 and Figure 5
present the distribution of service experience of Representatives and Senators, respectively, from
the 1st through 118th Congresses. For each Congress, the figures plot the percentage of each
chamber made up of the following four categories of Members: first-term Members with no prior
chamber service, returning Members with six years of chamber service or fewer, returning
Members with between 6 and 12 years of chamber service, and Members with more than 12 years
of chamber service.
House of Representatives
As shown in Figure 4, from Congress’s early years and throughout the 19th century, it was not
uncommon for 40% or more of the House to be made up of Members with no prior experience in
the chamber; in nine different Congresses during the century, Representatives with no previous
House experience made up half of the chamber or more.21 As the proportion of incoming
freshman Members began to decline around the turn of the 20th century, the proportion of
Representatives with more than 12 years of service began to increase. Members in this category
made up approximately 6% of the House in the 57th Congress (1901-1902); the figure peaked at
approximately 34% in the 111th Congress (2009-2010). As of the opening day of the 118th
Congress, approximately 23% of the chamber was made up of Representatives with more than 12
years of House service. Still, despite a general increase over time in longer-tenured Members, a
large proportion of the House was made up of Members with six or fewer years of chamber
experience during several recent Congresses.
Senate
Long-term trends in the distribution of Senate service generally mirror those in the House. In
contrast to the House, the Senate has generally had a smaller proportion of Members with no
prior chamber experience, even during Congress’s earlier history. The comparatively smaller
proportion of freshman Senators can be explained by the Senate’s staggered terms; because only
one-third of the chamber’s seats are up for election at a time, the amount of turnover resulting
from a single election year is limited. As can be seen in Figure 5, for much of congressional
history, the single largest group of Senators has been those with six years or fewer spent in the
chamber.
For much of the early history of Congress, relatively few Senators served for more than 12 years;
this group never exceeded 10% of the chamber until the 50th Congress (1887-1888). However, the
percentage in this category grew during the next few Congresses, and despite some fluctuation,

20 Samuel Kernell, “Toward Understanding 19th Century Congressional Careers: Ambition, Competition, and
Rotation,” American Journal of Political Science, vol. 21, no. 4 (November 1977), pp. 669-693; Joseph Schlesinger,
Ambition and Politics: Political Careers in the United States (Chicago: Rand McNally, 1966).
21 This includes the 15th (1817-1818), 28th (1843-1844), 31st (1849-1850), 32nd (1851-1852), 33rd (1853-1854), 34th
(1855-1856), 38th (1863-1864), 43rd (1873-1874), and 44th (1875-1876) Congresses.
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generally increased over much of the 20th and (to date) 21st centuries. The 103rd Congress (1993-
1994) marks the high point for Senators serving more than 12 years; this group of Senators made
up 47% of the chamber. As of the opening day of the 118th Congress, Members in this category
make up 43% of the chamber.
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Figure 4. Distribution of Member Tenure, House of Representatives
1st through 118th Congresses


Sources: CRS analysis of Biographical Directory of the United States Congress, ICPSR, and proprietary data. Inter-university Consortium for Political and Social Research,
and Carrol McKibbin, Roster of United States Congressional Officeholders and Biographical Characteristics of Members of the United States Congress, 1789-1996: Merged Data
[computer file] 10th ICPSR ed. (Ann Arbor: MI: Inter-university Consortium for Political and Social Research [producer and distributor], 1997).
CRS-10



Figure 5. Distribution of Member Tenure, Senate
1st through 118th Congresses

Sources: CRS analysis of Biographical Directory of the United States Congress, ICPSR, and proprietary data. Inter-university Consortium for Political and Social Research,
and Carrol McKibbin, Roster of United States Congressional Officeholders and Biographical Characteristics of Members of the United States Congress, 1789-1996: Merged Data
[computer file] 10th ICPSR ed. (Ann Arbor: MI: Inter-university Consortium for Political and Social Research [producer and distributor], 1997).
CRS-11

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Congressional Careers: Service Tenure and Patterns of Member Service, 1789-2023

Cross-Chamber Experience
A second issue related to patterns of congressional service is cross-chamber experience of
Senators and Representatives. While Senators have infrequently gone on to serve in the House,
Representatives who subsequently serve in the Senate have been common throughout U.S.
history. Figure 6 plots the percentage of Representatives and Senators with previous experience
in the other chamber from the 1st through 118th Congress.
Figure 6. Percentage of Members with Cross-Chamber Experience
1st through 118th Congresses

Source: CRS analysis of Biographical Directory of the United States Congress, ICPSR, and proprietary data. Inter-
university Consortium for Political and Social Research, and Carrol McKibbin, Roster of United States
Congressional Officeholders and Biographical Characteristics of Members of the United States Congress, 1789-1996:
Merged Data
[computer file] 10th ICPSR ed. (Ann Arbor: MI: Inter-university Consortium for Political and Social
Research [producer and distributor], 1997).
Senators with Prior House Experience
As shown in Figure 6, throughout American history, a sizable proportion of Senators have arrived
with prior service in the House, and the proportion has remained within a fairly constant range
over time. After Congress’s initial formation (when prior experience in one chamber was not
possible), the proportion of Senators with House experience fluctuated between 20% and 45% for
much of congressional history. In recent history, more than half of Senators serving at the start of
the 109th (2005-2006), 113th (2013-2014), and 114th (2015-2016) Congresses had previous House
experience. At the start of the 118th Congress, 44 of 100 Senators (44%) had previously served in
the House.
Representatives with Prior Senate Experience
Historically, a small but declining number of Members have served in the House of
Representatives after serving in the Senate. Figure 6 also plots the percentage of Representatives
in each Congress who had previously served in the Senate.
As can be seen in Figure 6, prior to the 1840s, it was common for several Representatives to have
previously served in the Senate. This group included such notable figures as Henry Clay, and
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former President John Quincy Adams. Over time, it became less common for Representatives to
have Senate experience. The last Representative to have previously served in the Senate was
Claude Pepper, who served in the Senate from 1936 until 1951, and in the House from 1963 until
1989.
Amount of Cross-Chamber Experience
A related question is how much prior House experience, on average, Senators have. Figure 7
plots the average years of House service among Senators, by Congress. The bottom line is the
average amount of House service among all Senators who began a given Congress; the top line is
the average amount of House service among Senators who previously served in the House.
Figure 7. Average Years of House Service Among Senators
1st through 118th Congresses

Sources: CRS analysis of Biographical Directory of the United States Congress, ICPSR, and proprietary data. Inter-
university Consortium for Political and Social Research, and Carrol McKibbin, Roster of United States
Congressional Officeholders and Biographical Characteristics of Members of the United States Congress, 1789-1996:
Merged Data
[computer file] 10th ICPSR ed. (Ann Arbor: MI: Inter-university Consortium for Political and Social
Research [producer and distributor], 1997).
As shown in Figure 7, Senators with prior House experience typically averaged between five and
nine years in the House prior to serving in the Senate. In the 118th Congress, the 46 Senators with
prior House service spent an average of 9.5 years in the House—four-and-three-quarter terms—
prior to serving in the Senate.
Concluding Observations
Aggregate statistics on Member service tenures tend to disguise the variety of congressional
service records found among individual Members. Some Members have very short tenures of
service and choose not to seek reelection; other Members have long tenures that end after
reelection defeat. At the aggregate level, average careers have become longer, but a great deal of
variation in the length of congressional careers still persists.
Additionally, the institutional and policy contexts that have shaped Member decisions to seek or
not seek reelection, and succeed or fail when seeking reelection, are not static factors. Just as the
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institutional contexts of elections and congressional operations have developed since the 19th
century, they continue to change in the contemporary Congress. To the degree that patterns of
congressional service in part reflect the incentives provided to Members by these institutional
factors, it is likely that the patterns of Member service tenure will also continue to change.
Similarly, the continued development of the institutional environment suggests that there is no
way to predict how the patterns of service tenure will change; just as seemingly stable 19th
century patterns rapidly changed toward the end of the century, so could the service tenure
patterns we observe today.

Author Information

Sarah J. Eckman
Amber Hope Wilhelm
Analyst in American National Government
Visual Information Specialist



Acknowledgments
Tyler Wolanin, Research Assistant in the Government and Finance Division, contributed to data updates
for this report. Former CRS analysts Matthew E. Glassman and William T. Egar authored previous versions
of this report. The listed author updated this report and is available to respond to inquiries on the subject
from congressional clients.

Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan
shared staff to congressional committees and Members of Congress. It operates solely at the behest of and
under the direction of Congress. Information in a CRS Report should not be relied upon for purposes other
than public understanding of information that has been provided by CRS to Members of Congress in
connection with CRS’s institutional role. CRS Reports, as a work of the United States Government, are not
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Congressional Research Service
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