First introduced in 1997, the Cook PVI measures how each district performs at the presidential level compared to the nation as a whole. We have released new PVI scores following every election since 1996 and every round of redistricting since 2001, each time taking into account the prior two presidential elections.
2017 PVI Report Full report of the 20th anniversary edition of the Partisan Voter Index (PVI) Visit Page
Most Republican to Most Democratic Districts A ranking of every House district in the 115th Congress from most Republican to Most Democratic. Visit Page