Partisan gerrymandering of electoral districts has infected American elections since the beginning of the republic. In recent decades, state legislatures—which, for the most part, draw the lines—have honed the practice into a political tool to ensure that a political party retains a majority (or supermajority) in the state even though such majorities do not reflect actual vote totals. Extreme partisan gerrymandering has become easier as political operatives have grown more savvy in this field and are able to access increasingly powerful mapping and data analysis tools.

A typical example is the state of Wisconsin. In 2016, 49.8% of the voters cast ballots for Democratic party candidates running for Congress. Yet, as a result of the Republican-controlled legislature that drew the district lines, five Republicans were elected to congress, and only three Democrats were. To be sure, Democrats have done this in the past as well. In Maryland, in 2016, despite a Democratic vote that was only 60% of the vote total, democrats received seven out of eight congressional seats.