u/ptrdo

When new maps disperse voters into opposition districts—as done recently in Tennessee—this triggers a ripple effect that moves a corresponding number of opposition voters elsewhere. Margins get redistributed, too, making safe districts more competitive.

Gerrymandering is a zero-sum game. As maps are engineered more aggressively, margins can get thinner and more vulnerable to political shifts.

…Except when voting is suppressed or discouraged—even a competitive district is winnable if only one party shows up.

When districts align with communities that share similar political preferences, many seats are relatively safe. But gerrymandering also rearranges margins: votes used to neutralize opposition in one district can no longer reinforce safer margins elsewhere. As maps become more aggressively engineered, margins can become thinner and more vulnerable to political shifts. Further, these maps are based on expectations of who HAS voted — not necessarily everyone who CAN vote.

Louisiana’s presidential election shifted dramatically from Democratic to Republican between 1996 and 2024—but turnout barely changed, and the electorate remained roughly the same.

Original Content. Election data: Federal Election Commission Turnout data: University of Florida Election Lab

Photo source (Dan Guravich), https://kennedyhumanrights.org/image/tour-of-the-mississippi-delta-4/

These two charts compare Louisiana’s 2022 and 2024 congressional maps, showing how the same population is assigned to districts differently—and how that changes the concentration of populations within districts.

This chart compares three election sequences (1960–1968, 2000–2008, and 2016–2024) to put the 2020 U.S. presidential election in the context of normal historical swing patterns. Original content. Data source: American Presidency Project, University of California, Santa Barbara presidency.ucsb.edu/statistics/elections