n 1999, there were 164 House districts where the election outcomes were within a five-point margin of the national popular vote. Currently, that number has decreased to 82, largely due to gerrymandering. This trend could heavily influence which party controls the House of Representatives by 2025.
The Cook Political Report categorizes “swing districts” as those where results fall within five points of the national vote. For example, if the national vote is evenly split, a swing district would have a five-point margin favoring either party. Over the past 25 years, the total count of competitive districts has been halved, with most now concentrated in just two states: New York and California.