The Cook Partisan Voting Index, abbreviated PVI or CPVI, is a measurement of how partisan [1] a United States congressional district or state is. This partisanship [2] 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. [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". [5] [6] [7] It is based on the methodology introduced by Rob Richie of the Center for Voting and Democracy (FairVote for the Center's July 1997 Monopoly Politics report. [8] [9]
The Cook Political Report has since released new PVI scores every two years. [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. [10] In 2022, the formula was updated to weigh the most recent presidential election more heavily than the prior election. [11]
The PVIs for congressional districts are calculated based on the 2016 and 2020 presidential elections. [11] 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. [11] As of 2022 [update] , in the House, there are 222 districts 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. [11]
The PVIs for states are calculated based on the results of the U.S. presidential elections in 2016 and 2020. [13] The table below reflects the current state of Congress and governors, based on the most recent election results.
State | PVI | Party of governor | Party in Senate | House balance |
---|---|---|---|---|
Alabama | R+15 | Republican | Republican | 6R, 1D |
Alaska | R+8 | Republican | Republican | 1D |
Arizona | R+2 | Democratic | Democratic* | 6R, 3D |
Arkansas | R+16 | Republican | Republican | 4R |
California | D+13 | Democratic | Democratic | 40D, 12R |
Colorado | D+4 | Democratic | Democratic | 5D, 3R |
Connecticut | D+7 | Democratic | Democratic | 5D |
Delaware | D+7 | Democratic | Democratic | 1D |
Florida | R+3 | Republican | Republican | 20R, 8D |
Georgia | R+3 | Republican | Democratic | 9R, 5D |
Hawaii | D+14 | Democratic | Democratic | 2D |
Idaho | R+18 | Republican | Republican | 2R |
Illinois | D+7 | Democratic | Democratic | 14D, 3R |
Indiana | R+11 | Republican | Republican | 7R, 2D |
Iowa | R+6 | Republican | Republican | 4R |
Kansas | R+10 | Democratic | Republican | 3R, 1D |
Kentucky | R+16 | Democratic | Republican | 5R, 1D |
Louisiana | R+12 | Republican | Republican | 5R, 1D |
Maine | D+2 | Democratic | Both* | 2D |
Maryland | D+14 | Democratic | Democratic | 7D, 1R |
Massachusetts | D+15 | Democratic | Democratic | 9D |
Michigan | R+1 | Democratic | Democratic | 7D, 6R |
Minnesota | D+1 | Democratic | Democratic | 4D, 4R |
Mississippi | R+11 | Republican | Republican | 3R, 1D |
Missouri | R+10 | Republican | Republican | 6R, 2D |
Montana | R+11 | Republican | Both | 2R |
Nebraska | R+13 | Republican | Republican | 3R |
Nevada | R+1 | Republican | Democratic | 3D, 1R |
New Hampshire | D+1 | Republican | Democratic | 2D |
New Jersey | D+6 | Democratic | Democratic | 9D, 3R |
New Mexico | D+3 | Democratic | Democratic | 3D |
New York | D+10 | Democratic | Democratic | 16D, 10R |
North Carolina | R+3 | Democratic | Republican | 7D, 7R |
North Dakota | R+20 | Republican | Republican | 1R |
Ohio | R+6 | Republican | Both | 10R, 5D |
Oklahoma | R+20 | Republican | Republican | 5R |
Oregon | D+6 | Democratic | Democratic | 4D, 2R |
Pennsylvania | R+2 | Democratic | Democratic | 9D, 8R |
Rhode Island | D+8 | Democratic | Democratic | 2D |
South Carolina | R+8 | Republican | Republican | 6R, 1D |
South Dakota | R+16 | Republican | Republican | 1R |
Tennessee | R+14 | Republican | Republican | 8R, 1D |
Texas | R+5 | Republican | Republican | 25R, 13D |
Utah | R+13 | Republican | Republican | 4R |
Vermont | D+16 | Republican | Democratic* | 1D |
Virginia | D+3 | Republican | Democratic | 6D, 5R |
Washington | D+8 | Democratic | Democratic | 8D, 2R |
West Virginia | R+22 | Republican | Both* | 2R |
Wisconsin | R+2 | Democratic | Both | 6R, 2D |
Wyoming | R+25 | Republican | Republican | 1R |
* Includes an independent senator who caucuses with the Democrats. |
Since Colorado became a U.S. state in 1876, it has sent congressional delegations to the United States Senate and United States House of Representatives, beginning with the 44th United States Congress. Prior to statehood, the Colorado Territory sent non-voting delegates to the House of Representatives from 1861 to 1876. Each state elects two senators to serve for six years, and members of the House to two-year terms. Each state elects two senators to serve for six years in general elections, with their re-election staggered. Prior to the ratification of the Seventeenth Amendment in 1913, senators were elected by the Colorado General Assembly. Each state elects a varying number of, but at least one, member of the House, depending on population, to two-year terms. Colorado has sent eight members to the House in each congressional delegation since the 2020 United States Census.
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Texas's 15th congressional district of the United States House of Representatives includes a thin section of the far south of the state of Texas. The district's current Representative is Republican Monica De La Cruz. Elected in 2022, de la Cruz is the first Republican and woman to represent the district.
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New York's 24th congressional district is located in Upstate New York in the Finger Lakes region, stretching alongside Lake Ontario from near Buffalo in the west to Watertown in the east. The district does not include Rochester, which is in the 25th district. Since 2023, it has been represented by Claudia Tenney. In the 2022 election it voted more strongly Republican than any other district in the state. Prior to the redistricting which took effect in 2023, the district included the city of Syracuse.
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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.
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.