Congressional Districts are the 435 areas from which people are elected to the U.S. House of Representatives. After the apportionment of congressional seats among the states based on decennial census population counts, each state with multiple seats is responsible for establishing congressional districts for the purpose of electing representatives. Each congressional district is to be as equal in population to all other congressional districts in a state as practicable. For the District of Columbia, Puerto Rico, and each Island Area, a separate code is used to identify the entire areas of these state-equivalent entities as having a single nonvoting delegate.
Congressional District Codes—Congressional districts are identified by a two-character numeric Federal Information Processing Series (FIPS) code numbered uniquely within state. The District of Columbia, Puerto Rico, and the Island Areas have code 98 assigned identifying their nonvoting delegate status with respect to representation in Congress:
01 to 53—Congressional district codes
00—At large (single district for state)