The 2015 cartographic boundary KMLs are simplified representations of selected geographic areas from the U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB). These boundary files are specifically designed for small-scale thematic mapping. When possible, generalization is performed with the intent to maintain the hierarchical relationships among geographies and to maintain the alignment of geographies within a file set for a given year. Geographic areas may not align with the same areas from another year. Some geographies are available as nation-based files while others are available only as state-based files.

                             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 census population counts, each state 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.  The 114th Congress is seated from January 2015 to 2017. The cartographic boundary
                             files for the District of Columbia, Puerto Rico, and the Island Areas (American Samoa, Guam, the Commonwealth of the Northern Mariana
                             Islands, and the U.S. Virgin Islands) each contain a single record for the non-voting delegate district in these areas.  The boundaries
                             of all other congressional districts are provided to the Census Bureau through the Redistricting Data Program (RDP).