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 is responsible for establishing the boundaries of the 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.

The 2013 TIGER/Line Shapefiles contain the 113th Congressional Districts. All congressional districts appearing in the 2013 TIGER/Line Shapefiles reflect the information provided to the Census Bureau by the states. The 113th Congressional District shapefile contains the areas in effect January 2013 to 2015.

Each state has a minimum of one representative in the U.S. House of Representatives. The District of Columbia, Puerto Rico, American Samoa, Guam, and the U.S. Virgin Islands have a non-voting delegate in the Congress.

Congressional District Codes—Congressional districts are identified by a 2-character numeric FIPS code. Congressional districts are numbered uniquely within state. The District of Columbia, Puerto Rico and the Island areas have the code of 98, which identifies their status with respect to representation in Congress:

01 to 53—Congressional district codes
00—At large (single district for state)
98—Nonvoting delegate