Cook Partisan Voting Index

[3][4] The Partisan Voting Index was developed in 1997 by Charlie Cook of The Cook Political Report, in conjunction with Clark Bensen and his political statistical analysis firm, Polidata, "as a means of providing a more accurate picture of the competitiveness".

[10] In 2021, the newsletter ended its relationship with Polidata and instead used Dave Leip's Atlas of U.S. Presidential Elections to calculate 2020's results.

[7] The most recent iteration is the 2022 Cook Partisan Voting Index, which was released with an updated formula for calculating PVI values.

[11] The index looks at how every congressional district voted in the past two presidential elections combined and compares it to the national average.

[12] The Cook PVI is displayed as a letter, a plus sign, and a number, with the letter (either a D for Democratic or an R for Republican) indicating the party that outperformed in the district and the number showing how many percentage points above the national average it received.

Map of 2016 – 2020 Cook PVI for all voting entities in the 2024 United States presidential election ( states , federal district , congressional districts of Maine and Nebraska )

Map legend:
State or district has a Cook PVI of D+10 or greater
State or district has a Cook PVI between D+5 and D+10
State or district has a Cook PVI between D+2 and D+5
State or district has a Cook PVI between EVEN and D+2
State or district has a Cook PVI between EVEN and R+2
State or district has a Cook PVI between R+2 and R+5
State or district has a Cook PVI between R+5 and R+10
State or district has a Cook PVI of R+10 or greater