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What is apportionment?

Apportionment is the process of dividing the 435 memberships, or seats, in the U.S. House of Representatives among the 50 states based on the apportionment population counts from the decennial census.

Who is included in the apportionment population counts?

The apportionment population count for each of the 50 states includes the state’s total resident population (citizens and non-citizens) plus a count of the overseas federal employees (and dependents) who have that state listed as their home state in their employers’ administrative records.

For details on who is counted (and where they are counted) in the 2020 Census, see the 2020 Census Residence Criteria and Residence Situations.

Who is included in the resident population counts?

The resident population counts include all people (citizens and non-citizens) who are living in the United States at the time of the census. People are counted at their usual residence, which is the place where they live and sleep most of the time.

The resident population also includes military and civilian employees of the U.S. government who are deployed outside the United States (while stationed or assigned in the United States) and can be allocated to a usual residence address in the United States based on administrative records from the Department of Defense.

The resident population counts for the District of Columbia, Puerto Rico, and the U.S. Island Areas are not included in apportionment calculations (because those areas do not have voting seats in the U.S. House of Representatives), but they are included in other data products.

Note: The resident population counts are available down to the lowest levels of geography (i.e. census block), but only the state totals are used for apportionment. The more detailed resident population data are included in other census data products that are used for redistricting and many other purposes.

Who is included in the counts of overseas federal employees?

The counts of overseas federal employees include military and civilian employees of the U.S. government who are stationed or assigned outside the 50 states (and the District of Columbia) and their dependents living with them overseas. The counts also include U.S. military personnel assigned to U.S. military vessels that have a homeport outside the 50 states.

Also, some people who are deployed outside the United States (while stationed or assigned in United States) cannot be included in the resident population because administrative records are insufficient to allocate them to a usual residence address in the United States. In those cases, the Census Bureau will use administrative records from the Department of Defense to allocate them to their home state and include them in the counts of overseas federal employees.  

The counts exclude any overseas federal employees who cannot be successfully allocated back to their home state based on their employers’ administrative records. The counts also exclude private U.S. citizens living overseas who are not employed by the U.S. government.

Note: The counts of overseas federal employees are only available as state totals, and they are only used for apportionment. They are not included in any other census data products, and they are not used for redistricting.

How does the Census Bureau obtain the counts of overseas federal employees?

Agencies and departments of the U.S. government provide the Census Bureau with counts of their overseas employees (and their dependents living with them overseas) by their home state based on their administrative records.

Are undocumented residents included in the apportionment population counts?

Yes, all people (citizens and noncitizens) with a usual residence in the 50 states are included in the resident population for the census, which means they are all included in the apportionment counts.

Are children under 18 years old included in the apportionment population counts even though they cannot vote?

Yes, all people of all ages (even newborn babies) with a usual residence in the 50 states are included in the resident population for the census, which means they are all included in the apportionment counts. Being registered or eligible to vote is not a requirement for inclusion in the apportionment counts.

What is the mandate for conducting the apportionment?

Article I, Section 2 of the U.S. Constitution mandates that an apportionment of representatives among the states be carried out within every 10-year period.

How is the apportionment calculated?

The apportionment of seats in the U.S. House of Representatives is calculated every ten years using the method of equal proportions, according to the provisions of Title 2, U.S. Code. Congress decides the method used to calculate the apportionment. This method has been used in every census since the 1940 census. The method computes "priority values" based on each state's apportionment population. For more details, see How it’s Calculated.

Can the number of seats in the U.S. House of Representatives be increased?

Yes, the number of House seats can be increased by legislation enacted by Congress. However, the number of House seats has remained constant at 435 since 1911, except for a temporary increase to 437 at the time of admission of Alaska and Hawaii as states just prior to the apportionment in 1960.

What was the average number of people per representative based on the 2010 Census apportionment?

After the apportionment based on the 2010 Census, the average number of people per representative in the House was 710,767.

When are the apportionment population counts given to the President? To the Congress? To the states?

Title 13, U.S. Code requires that the apportionment population counts for each state be delivered to the President within 9 months of the census date, and it requires that the census date is April 1 of the census year. This means that the Office of the President must receive the counts by December 31 of the census year.

According to Title 2, U.S. Code, within one week of the opening of the next session of the Congress in the new year, the President must report to the Clerk of the U.S. House of Representatives the apportionment population counts for each state and the number of representatives to which each state is entitled.

Also according to Title 2, U.S. Code, within 15 days of receiving the apportionment population counts from the President, the Clerk of the House must inform each state governor of the number of representatives to which each state is entitled.

When will the apportionment population counts be released to the public? Will they be posted on the Internet?

A press release showing the apportionment results will be disseminated by December 31, 2020, through a wide variety of media channels, including the Internet. A news conference announcing the apportionment results will be held shortly after.

What is the difference between apportionment and redistricting?

Apportionment is the process of determining the number of representatives to which each state is entitled in the U.S. House of Representatives based on the decennial census. By law, the apportionment results must be submitted to the President by December 31 of the census year.

Redistricting is the process of revising the geographic boundaries of areas from which people elect representatives to the U.S. House of Representatives, a state legislature, a county or city council, a school board, etc. By law, redistricting data must be submitted to the states by April 1 of the year after the census.

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