The goal of the 2010 Census Federally Affiliated Overseas Count Operation was to obtain counts by home state of U.S. military and federal civilian employees stationed overseas and their dependents living with them. For the 2010 Census, overseas was defined as anywhere outside the 50 U.S. states and the District of Columbia. Counts were obtained from administrative records and were used to allocate the federally affiliated population living overseas to a home state for the purpose of reapportioning seats in the U.S. House of Representatives. Forty federal departments and agencies provided certified counts by home state for their federally affiliated employees living overseas. The federally affiliated population residing overseas has been officially included in the apportionment population in the 2010, 2000, 1990 and 1970 censuses based on the intentions of Congress.

For the 2010 Census, federal departments and agencies were sent a contact letter in October 2009 from the Secretary of Commerce and the Director of the Census Bureau requesting the name of a contact person with whom to coordinate the count effort. A second letter was sent to the designated contacts in February 2010 requesting the actual counts. This letter included: Form D-55, Counts of Federally Affiliated Overseas Personnel and Dependents by Home State of Residence; and, Form D-55A, Guidelines for Completing Form D-55. Completed forms were due back to the Decennial Management Division by July 9, 2010.

The Decennial Management Division compiled the federally affiliated overseas counts by home state from the certified forms and delivered these to the Population Division on August 17, 2010. The Population Division created apportionment counts and delivered the final apportionment tables to the Director of the Census Bureau in December 2010.