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Map Layer Info

One Million-Scale Congressional Districts of the United States

What this map layer shows:

The congressional district boundaries for the 113th Congress (2013-2014).
opens the U.S. Geological Survey home page
Background Information
Sample map
Sample Map
The U.S. Census Bureau is required to take a census of population every ten years, during the year ending with zero. According to the Constitution of the United States, this decennial census has one fundamental purpose: to ensure that number of seats each State has in the U.S. House of Representatives reflects the relative size of the State's population as compared with other States. Currently there are 435 representatives divided among the 50 States. Each of these representatives is elected by the voters of a congressional district, defined as an area established by law for the election of representatives to the U.S. Congress. Each congressional district is to be as equal in population to all other congressional districts in the State as practicable, based on the decennial census counts. The number of congressional districts in each State can change after a decennial census. After the number of seats assigned to the individual States is determined (apportionment), the task of drawing the new congressional districts (redistricting) is generally given to each State legislature. As a result of apportionment, the boundaries of the 113th Session of Congress changed.

Change in the Number of
U.S. Representatives by State - 2010
State Gain State Loss
Total 12 Total 12
Texas 4 New York 2
Florida 2 Ohio 2
Arizona 1 Illinois 1
Georgia 1 Iowa 1
Nevadaa 1 Louisiana 1
South Carolina 1 Massachusetts 1
Utah 1 Michigan 1
Washington 1 Missouri 1
    New Jersey 1
    Pennsylvania 1

The One Million-Scale Congressional Districts of the United States map layer portrays the congressional district boundaries for the 113th Congress (2013-2014). Descriptive information includes the full name and party affiliation of the congressional representative elected from each district and the congressional district number. Historical congressional district map layers for the 106th through 112th Congresses are also available for download from the National Atlas of the United States®.

This map layer was produced by the National Atlas of the United States. It is part of our collection of fundamental digital cartographic data known as 1. This collection includes base map data in vector format at 1:1,000,000 scale and in image format at 100-meter resolution. Read more about the 1. The 1 data are also available as Web Services.


Congressional Apportionment