thumb|360px|Map of [[2020 United States presidential election|2020–2024 Cook PVI for all voting entities in the 2028 United States presidential election (states, federal district, congressional districts of Maine and Nebraska)<br><br>Map legend:<br>]]
The Cook Partisan Voting Index, abbreviated PVI or CPVI, is a measurement of the partisanship of a U.S. congressional district or U.S. state. 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".
The Cook Political Report has since released new PVI scores every two years. The most recent iteration is the 2025 Cook Partisan Voting Index.
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 2020 and 2024 presidential elections. The table below reflects the state of Congress and governors, based on the 2024 election results.
Using the United States Census Bureau's official 2024 population estimates, a combined 182,737,780 residents live in the 29 states that lean Republican; 141,264,067 residents live in the 20 voting blocs (19 states plus Washington, D.C.) that lean Democratic; and 16,101,434 residents live in the two states (Michigan and Wisconsin) that lean neither Republican nor Democratic (PVI of EVEN).
{| class="wikitable sortable static-row-numbers"
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! scope="col" style="text-align:left;" | State
! scope="col" style="text-align:left;"| PVI
! scope="col" style="text-align:left;"| Last presidential<br/>election winner
! scope="col" style="text-align:left;"| Party of<br/>governor
! scope="col" style="text-align:left;"| Party<br/>in Senate
! scope="col" style="text-align:left;"| House<br/>balance
<!--
USE THIS FORMAT ONLY IF A STATE HAS A NON-DEMOCRATIC, NON-REPUBLICAN REPRESENTATIVE
The house balance values are sorted using the format: where:
X is the sort value, written out with 3 digits
Y is the house balance in the form #R, #D (or #D, #R depending on who has the majority)
The sort value = 999*#R/(#R+#D), rounded to the nearest integer
Example: Alabama (6R, 1D), the sort value = 999*6/7 = 856
Example: California (38D, 15R), the sort value = 999*15/53 = 282
Example: Iowa (Even 2–2), the sort value = 999*2/4 = 500
-->
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| Alabama
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| Alaska
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| Arizona
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| Arkansas
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| California
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| Colorado
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| Connecticut
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| Delaware
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| Florida
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| Georgia
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| Hawaii
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| Idaho
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| Illinois
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| Indiana
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| Iowa
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| Kansas
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| Kentucky
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| Louisiana
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| Maine
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| Maryland
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| Massachusetts
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| Michigan
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| Minnesota
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| Mississippi
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| Missouri
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| Montana
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| Nebraska
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| Nevada
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| New Hampshire
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| New Jersey
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| New Mexico
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| New York
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| North Carolina
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| North Dakota
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| Ohio
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| Oklahoma
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| Oregon
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| Pennsylvania
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| Rhode Island
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| South Carolina
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| South Dakota
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| Tennessee
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| Texas
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| Utah
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| Vermont
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| Virginia
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| Washington
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| Washington, D.C.
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| West Virginia
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| Wisconsin
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| Wyoming
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See also
- Political party strength in U.S. states
- Psephology, the statistical analysis of elections
- Two-party-preferred vote
Notes
References
External links
- The Cook Political Report