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The Cook Partisan Voting Index, abbreviated PVI or CPVI, is a measurement of how partisan a U.S. congressional district or U.S. state is. This partisanship is indicated as lean towards either the Republican Party or the Democratic Party, compared to the nation as a whole, based on how that district or state voted in the previous two presidential elections.

History

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". It is based on the methodology introduced by Rob Richie of the Center for Voting and Democracy for the Center's July 1997 Monopoly Politics report.

The Cook Political Report has since released new PVI scores every two years. 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. The most recent iteration is the 2022 Cook Partisan Voting Index, which was released with an updated formula for calculating PVI values.

Calculation and format

The index looks at how every congressional district voted in the past two presidential elections combined and compares it to the national average. 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. In 2022, the formula was updated to weigh the most recent presidential election more heavily than the prior election.

By congressional district

The PVIs for congressional districts are calculated based on the 2016 and 2020 presidential elections. With a PVI of R+1, Michigan's 8th congressional district was determined to be the median congressional district, meaning that exactly 217 districts are more Democratic and 217 are more Republican than this district. As of 2022, there are 222 districts in the House that are more Republican than the national average and 206 districts more Democratic than the national average. The number of swing seats, defined as those between D+5 and R+5, is 87.

By state

The PVIs for states are calculated based on the results of the U.S. presidential elections in 2016 and 2020. The table below reflects the state of Congress and governors, based on the 2022 election results.

See also

• Political party strength in U.S. states
• Psephology, the statistical analysis of elections
• Two-party-preferred vote

Notes

1. Includes an independent senator who caucuses with the Democrats
2. Includes an independent senator who caucuses with the Democrats
3. Includes an independent senator who caucuses with the Democrats
4. Mayor of the District of Columbia
5. Non-voting delegates
6. Includes an independent senator who caucuses with the Democrats

References

1. Paul, Megan; Zhang, Ruya; Liu, Bian; Saadai, Payam; Coakley, Brian A. (2022). "State-level political partisanship strongly correlates with health outcomes for US children". European Journal of Pediatrics. 181: 273–280. doi:10.1007/s00431-021-04203-y. PMID 34272984.
2. Cillizza, Chris (April 10, 2017). "A map that shows we really do live in two different Americas". CNN. Retrieved December 15, 2023.
3. Cillizza, Chris (March 14, 2018). "The differences between real grassroots and "Astroturf" matter". CNN. Retrieved November 29, 2020. Which brings me to the Cook Political Report's Partisan Voting Index or PVI. The goal of the PVI is to compare every congressional district to every other congressional district based on how it has performed in each of the last two presidential elections.
4. Benen, Steve (February 7, 2017). "There are 119 Republican House members who should be VERY nervous today". MSNBC. Retrieved November 29, 2020. To get a sense of a congressional district's political leanings, there's a helpful metric called the Partisan Voter Index, or PVI, created 20 years ago by the Cook Political Report.
5. Kurtz, Josh (June 8, 2005). "Future House Opportunities Abound (Maybe)". Roll Call. Retrieved December 22, 2023.
6. Daum, Courtenay; Duffy, Robert; Straayer, John, eds. (2011). State of Change. Boulder: University of Colorado Press. ISBN 978-1-4571-1154-9. Retrieved December 22, 2023.
7. ^ "The Cook Partisan Voting Index (Cook PVI)". The Cook Political Report with Amy Walter. Cook Political Report. Retrieved December 22, 2023.
8. Cook, Charlie (August 11, 1997). "New Study Identifies 75 Seats That Should Be In Play for '98 Election". Roll Call. Retrieved January 18, 2024.
9. "Monopoly Politics". Center for Voting and Democracy. July 1997. Retrieved January 18, 2024.
10. ^ Kane, Paul (April 8, 2023). "New report outlines the deep political polarization's slow and steady march". The Washington Post. Retrieved December 22, 2023.
11. ^ Wasserman, David (July 13, 2022). "Introducing the 2022 Cook Partisan Voting Index (Cook PVI)". The Cook Political Report with Amy Walter. Retrieved July 13, 2022.
12. Seib, Gerald (December 9, 1998). "GOP Moderates and the Agony Of Their Impeachment Choice". The Wall Street Journal. Retrieved December 22, 2023.
13. "2022 Cook PVI: State Map and List". The Cook Political Report with Amy Walter. July 12, 2022. Retrieved July 19, 2022.

External links

• The Cook Political Report

• Psephology
• United States congressional districts
• The Cook Political Report with Amy Walter