About Redistricting

This website provides information about the redistricting process in Pennsylvania, including information about the Legislative Reapportionment Commission created by the state Constitution, access to the geography and population data used for redistricting, interactive maps, and more.

Redistricting is the process by which the boundaries of elective districts are periodically redrawn to maintain equal representation on the basis of population.

Article 1, Section 2, of the United States Constitution requires that a Census be taken every 10 years for the purpose of apportioning the United States House of Representatives. Census results are used to determine the number of congressional seats apportioned to each state. After the 2000 federal Census, Pennsylvania had 19 members in the U.S. House of Representatives. Following the 2010 federal Census, Pennsylvania had 18 members of the U.S. House. Following the 2020 Census, Pennsylvania's population, while growing by 2.1%, grew more slowly than the country, and subsequently resulted in a reduction to 17 seats. More information on the Census is available at census.gov

In addition to being used as a basis for apportioning seats in the U.S. House of Representatives, Census data is also used in Congressional and Legislative redistricting.

Public Law 94-171, enacted by Congress in December 1975, requires the Census Bureau to deliver redistricting data to state officials responsible for legislative redistricting no later than April 1, 2021. Delays caused primarily by COVID-19 necessitated a delay in the delivery of redistricting data. More information on the redistricting data program is available on the U.S. Census Bureau website.