In August of 1997, the Cook Political Report introduced the Cook Partisan Voting Index (Cook PVI) to provide a more accurate picture of the competitiveness of each of the 435 congressional districts. With the 2022 PVI release, we made a slight change to how we calculate PVI scores: instead of using a 50/50 mix of the two most recent presidential elections to assess partisanship as we had done in the past, we switched to a 75/25 weighting in favor of the more recent presidential cycle. Using the updated formula, we are now re-releasing PVI scores for every Congress since the 105th (1997-1998).
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Active CPR subscribers can request the Cook PVI data in spreadsheet format.
Map shapefile: Jeffrey B. Lewis, Brandon DeVine, Lincoln Pitcher, and Kenneth C. Martis. (2013) Digital Boundary
Our subscribers have first access to individual race pages for each House, Senate and Governors race, which will include race ratings (each race is rated on a seven-point scale) and a narrative analysis pertaining to that race.