An interesting effect of gerrymandering

[mprotsenko]

just 16 of 435 districts "crossed over" to vote for presidential and House candidates of opposite parties, down from 35 in 2016 and 108 in 1996. Today, there are nine Republicans sitting in districts Biden carried, and seven Democrats in districts Trump carried. This beats 2012's record low of 26 districts.

https://www.cookpolitical.com/analysis/national/pvi/introducing-2021-cook-political-report-partisan-voter-index

From 1996 to 2020 a number of crossover discricts (voting for one party in House elections and for another in presidential) - got not just smaller, but 6.75 times smaller, basically disappearing.