CityLab discusses a University of Richmond project to map Congressional elections going back to 1840:
“Electing the House” makes the most robust and comprehensive dataset to-date of Congressional elections available in a user-friendly format, offering additional dimension of insight into the current political moment. It is the first part of a series, which may include visualizations of historical data on Senate elections in the future. Theproject features an interactive map, presenting each district color-coded based on the party that won in each Congressional election between 1840 and 2016. Toggling the option in the legend can isolate just the districts that have flipped one way or the other for each election year. (The first Congress was elected in 1788, but the researchers started with 1840 because that’s the year the data become sufficiently reliable.)
The interactive also allows users to view the data in the form of a cartogram, where each district is represented as a discrete bubble and the ones in populous metropolitan areas cluster together. This version gives a sense of the rural-urban divide in political representation over time. By clicking on a single district, the interactive allows users to explore its particular political trajectory.
The map also allows users to trace the constantly changing geography of Congressional districts—through regular redistricting and partisan gerrymandering. Below are a series of maps showing the evolution of North Carolina’s 12th district—the most gerrymandered district in America, according to an analysis by the Washington Post. “It snakes from north of Greensboro, to Winston-Salem, and then all the way down to Charlotte, spanning most of the state in the process,” writes the Post’s Christopher Ingraham. It’s been drawn up this way by Republicans to squeeze their opponents’ supporters into one Congressional district. You can see it getting skinner and more irregular over time.
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