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The geographies of United States congressional districts yield tremendous political power. I live in the Pennsylvania 5th district; Rep. Glenn Thompson [R] is our elected voice in the U.S. House of Representatives. The PA 5th is Pennsylvania’s largest district by area, and while it consistently elects Republican representatives, small strongholds of Democratic voters live in places like State College.

Districts are notorious for gerrymandering. Recently, a federal judge ruled that the North Carolina 1st and 12th districts violated the Equal Protection Clause of the Fourteenth Amendment because their geographies were so aggressively designed to weaken the voting power of African Americans.

Perhaps the wildest geography of any U.S. congressional district is the Maryland 3rd, which snakes around Baltimore, then southwest all the way to within five miles of the District of Columbia, and then back east along the Chesapeake, finally finishing in Annapolis. It’s impossible to drive from one end of this district to the other without leaving its boundaries.

Congressional districts within California and Georgia seem relatively tame and sensible.

Explore other districts on this map of constituent regions for the 114th United States Congress.

About the maps

These maps are a product of a project I undertook with to redesign congressional district maps and migrate the technology behind them to Mapbox.

As part of this project, I created a tool for coloring areas on a map with one of five colors such that no bordering areas are the same color. While it’s possible to do the same with four colors, that would require handling 4,176 special cases. Five colors was good enough for me. I found this post helpful.

Special thanks to Josh Tauberer for his guidance on this project.

I describe the exact process used to produce these maps here.