The decennial census of housing and population is conducted every 10 years to count each resident of the United States and its territories, as well as military personnel and dependents abroad. The constitutionally mandated purpose of the decennial census is to determine the apportionment of the seats in the U.S. House of Representatives. Per Article I, Section 2, clause 3 of the U.S. Constitution, every 10 years an "actual [e]numeration" must be conducted "in such Manner as [Congress] shall by Law direct."
Recently, the Census Bureau published a notice of proposed rulemaking and requested comments on operational revisions to the decennial census for 2030. The proposed rule includes residence criteria that would exclude from the apportionment count all citizens of foreign countries who are not either also citizens of the United States or lawful permanent residents of the United States. The proposed rule also describes methods that might be used to determine a respondent's citizenship status. The Federal Register notice indicates that comments on the proposed rule must be received by October 13, 2026.
The Census Bureau aims to count every person during the decennial census only once and in the right place. To ensure individuals are counted at the right place, the Census Act of 1790 introduced the concept of a "usual residence." In a document for the 2020 decennial census, the Census Bureau defined usual residence as "the place where a person lives and sleeps most of the time," which may not necessarily be the person's legal residence, voting residence, or where they may want to be counted. Residence criteria have varied over time.
The Census Bureau published the final residence criteria in the Federal Register in advance of the 2020 census. The criteria used to determine usual residence for 2020 indicated the definition of usual residence; how foreign citizens living in the United States are counted; that foreign citizens visiting the United States are excluded; how military or civilian employees outside the United States are counted; and how college students away from home are counted.
On September 10, 2026, the Census Bureau proposed revisions to the residence criteria to be used during the 2030 census. These new criteria propose to include "lawful permanent residents" (also known as green card holders) within the apportionment base and exclude from the apportionment base "illegal aliens and aliens whose legal status is less durable and indefinite in length than lawful permanent resident status." This exclusion would potentially cover not only persons unlawfully present in the United States but also some persons lawfully present. The proposed 2030 criteria also address how other groups are counted, including U.S. military and federal civilian employees abroad, persons who are born or die on or after census day, persons incarcerated in detention facilities, and dependents, among others.
To determine an individual's legal status, the Census Bureau is considering utilizing administrative records from various federal agencies; state, local, and tribal records; and third-party commercial data. Additionally, the Census Bureau indicates that it could include a question about the respondent's citizenship status on the decennial census questionnaire.
Leading up to the 2020 decennial census, the Trump Administration planned to include a question on the decennial census asking for the respondent's citizenship status. This effort was blocked by the Supreme Court, which found that the Commerce Secretary's rationale for adding the question to enforce the Voting Rights Act "seem[ed] to have been contrived." Though the rationale for adding a citizenship question caused the Court to block it for 2020, the Court held that the decennial census could ask about citizenship so long as there was appropriate rationale to do so.
All but one decennial census between 1820 and 1950 included some form of a citizenship question. Additionally, the "long form" census asked a subset of households about citizenship between 1970 and 2000, after which that product was replaced by the American Community Survey (ACS), which currently asks about citizenship. No citizenship question has been asked on the "short form" census distributed to most households since 1950.
A citizenship question was included in operational tests in 2019 and in 2026.
During the 2019 census test, results from respondents who were asked a citizenship question were compared with results from those who were not. The test found no statistically significant difference in overall self-response rates. However, the test found statistically significantly lower response rates in some areas and subgroups—for example, some Hispanic respondents had statistically significantly lower responses to the citizenship question sample.
The 2026 census test was conducted using the ACS questionnaire for all respondents, which included a citizenship question. Results from the 2026 census test have not yet been released.
Some Members of Congress have introduced legislation that would require a citizenship question and exclude noncitizens from apportionment; other Members have introduced legislation that would prohibit a citizenship question. None of the introduced bills related to a citizenship question on the census have been signed into law.
Members of Congress may also wish to conduct oversight with respect to various dimensions of this proposal. For example, Members of Congress may be interested in the proposed rule's potential impacts on the apportionment base determined from the 2030 census, because if the proposed rule takes effect, noncitizens who have historically been included in the apportionment count will be excluded, which could change the distribution of seats in the House of Representatives.
Additionally, Members of Congress may have interest in how the Census Bureau would use administrative records from government and private commercial sources to make official determinations for the apportionment base. Furthermore, Members may be interested in knowing what specific commercial data sources are being considered by the Census Bureau.