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Partisan Voter Index|By David Wasserman, April 4, 2013
Click here for the 2017 update

The Cook Political Report is pleased to introduce the new 2014 Partisan Voter Index (PVI) for all 50 states and 435 Congressional districts in the country, compiled especially for the Report by POLIDATA®. First introduced in 1997, the Cook PVI measures how each district performs at the presidential level compared to the nation as a whole. In October 2012, we released new PVI scores for newly redrawn Congressional districts following redistricting. This release has updated our PVI scores to incorporate the results of the November 2012 presidential election.

The 2012 presidential results by district are remarkable in their own right: Republican presidential nominee Mitt Romney carried 226 districts to President Obama's 209, while losing the race by nearly four percent. This helps explain why House Democrats won 1.4 million more votes than House Republicans in 2012 but won just 201 of 435 seats. The House is well-sorted out: there are only 17 Republicans sitting in districts Obama carried, and only nine Democrats sitting in districts Romney carried.

This year's Partisan Voter Index illustrates how voters' geographical self-sorting, even more than redistricting, has driven the polarization of districts over the last decade. The 2012 round of redistricting diminished the number of "Swing Seats" - those with PVI scores between R+5 and D+5 - from 103 to 99. But after the November 2012 election, the number of "Swing Seats" fell even more sharply, from 99 to 90. This means the number of competitive-range districts has fallen a total of 45 percent, from 164 to just 90, between 1998 and 2013.

More evidence voters are choosing sides with their feet: in the 2012 election, 76 percent of Democratic-held seats grew even more Democratic and 60 percent of Republican-held seats grew even more Republican, not taking into account redistricting. As a result, whereas the median Democratic-held seat had a D+7 PVI score in 1998, the median Democratic seat has a D+12 PVI score today. The median Republican-held seat had an R+7 PVI score in 1998; the median Republican-held seat has an R+10 PVI score today.

This sorting has not only amplified the ability of redistricters to partition states into safe seats. It has hurt Democrats, whose voters are disproportionately clustered on the map. The most Republican district in the country is Rep. Mac Thornberry's TX-13, with a score of R+32. But Democrats hold 15 districts with a PVI score of D+32 or higher. Overall, there are 247 House seats more Republican than the national average, and 188 seats more Democratic. This means Democrats would need to hold all Democratic-leaning seats and win 30 Republican-leaning seats to win a majority.

Subscribers can view the full 2014 Partisan Voter Index in three different formats below:

2014 Partisan Voter Index by State and District »

2014 Partisan Voter Index by Member Name »

2014 Partisan Voter Index by Partisan Rank »

Before & After the 2012 Election: Partisan Distribution of the House

In many respects, observing House Democrats trying to take back their majority is like watching a soccer team play a comparably skilled opponent with the field slanted 15 degrees against them. After redistricting but before the 2012 election, there were 190 strongly Republican seats and 146 strongly Democratic seats, forcing Democrats to win 72 of the remaining 99 seats for a majority. After the 2012 election, there are 186 strongly Republican seats and 159 strongly Democratic seats, a narrower gap.

However, most of the growth in strongly Democratic seats has come from the ranks of moderately Democratic seats, particularly Hispanic majority districts where Republicans once performed competitively at the presidential level but floundered across the board in 2012. Meanwhile, there are 36 moderately Republican districts in addition to 186 strongly Republican districts, more than enough for a majority. For Democrats, winning not only all barely Democratic districts but all barely Republican districts would still only produce 213 seats.

Before & After the 2012 Election: Partisan Distribution of the House

District Type Before 2012 After 2012 Difference
Strongly Republican (R+5 or Greater)
Moderately Republican (R+2 to R+5)
Barely Republican (EVEN to R+2)
Total Republican
Barely Democratic (EVEN to D+2)
Moderately Democratic (D+2 to D+5)
Strongly Democratic (D+5 or Greater)
Total Democratic

The Decline of the "Swing Seat"

The most striking House statistic in the last 15 years may be the decline of competitive districts, places where members have the most incentives to work on a bipartisan basis. In 1998, our Partisan Voter Index scored 164 districts between D+5 and R+5, more than a third of the House, and greater than both the number of strongly Democratic and strongly Republican seats. After the 2012 election, there are only 90 districts between D+5 and R+5 – less than a quarter of the House and a 45 percent decline since 1998.

Redistricting is only responsible for a portion of the swing seat decline. In many minimally altered districts, the electorate has simply become much more homogenous. For example, the boundaries of WestVirginia’s 2nd CD have barely changed since 1998, but its PVI score has shifted from EVEN to R+11 as its voters have moved away from the national Democratic brand. Likewise, Albuquerque’s migration to the left has bumped the PVI score of New Mexico’s 1st CD from R+1 to D+7.

But this voter self-sorting has also enabled partisan gerrymanderers to more easily polarize districts wherever they wield power over the map. As Robert Draper astutely observed in The Atlantic, the goal of partisan mapmakers is often to “design wombs” for your team and “tombs for the other guys.” In the case of Northern Virginia’s 11th CD, Republicans actually boosted Democratic Rep. Gerry Connolly’s PVI from D+2 to D+7 in order to make neighboring districts more Republican; Connolly's district is now D+10 following the 2012 election.

There is also strong evidence the "trading range" of what constitutes a truly competitive seat has narrowed in the past 15 years as split-ticket voting has declined. In 1998, Republicans held nine of the 43 seats between D+2 and D+5 and six of the 123 seats greater than D+5, and Democrats held 15 of the 53 seats between R+2 and R+5 and 14 of the 148 seats greater than R+5. But in 2012, Republicans held zero of the 19 seats between D+2 and D+5 and just one of the 159 seats greater than D+5, while Democrats held just four of the 36 seats between R+2 and R+5 and just five of the 186 seats greater than R+5.

Partisan Voter Index (PVI) Summary: 2014 vs. 2000

1992/1996 Summary: Going Into the 2000 Elections

Democratic-Held Seats
D+10.0 or Greater D+5.0 to D+9.9 D+2.0 to D+4.9 D+1.9 to R+1.9 R+2.0 to R+4.9 R+5.0 to R+9.9 R+10.0 or Greater








Republican-Held Seats
D+10.0 or Greater D+5.0 to D+9.9 D+2.0 to D+4.9 D+1.9 to R+1.9 R+2.0 to R+4.9 R+5.0 to R+9.9 R+10.0 or Greater








D+10.0 or Greater D+5.0 to D+9.9 D+2.0 to D+4.9 D+1.9 to R+1.9 R+2.0 to R+4.9 R+5.0 to R+9.9 R+10.0 or Greater











2008/2012 Summary: Going Into the 2014 Elections

Democratic-Held Seats
D+10.0 or Greater D+5.0 to D+9.9 D+2.0 to D+4.9 D+1.9 to R+1.9 R+2.0 to R+4.9 R+5.0 to R+9.9 R+10.0 or Greater








Republican-Held Seats
D+10.0 or Greater D+5.0 to D+9.9 D+2.0 to D+4.9 D+1.9 to R+1.9 R+2.0 to R+4.9 R+5.0 to R+9.9 R+10.0 or Greater








D+10.0 or Greater D+5.0 to D+9.9 D+2.0 to D+4.9 D+1.9 to R+1.9 R+2.0 to R+4.9 R+5.0 to R+9.9 R+10.0 or Greater











One silver lining for Democrats in this new reality may be that Democrats have demonstrated modestly more "staying power" in Republican-leaning seats than vice versa. After the 2012 elections, there were only 18 Democrats remaining in Republican-leaning seats, compared to 50 in 1998. But after 2012, perhaps as a testament to a badly damaged GOP brand, there were only five Republicans remaining in Democratic-leaning seats, compared to 37 in 1998. Overall, these "crossover" districts have plummeted from 87 in 1998 to just 23 in 2013.

The downside, of course, is that Democrats retain more exposure in these kinds of seats than Republicans:

The Ten Democrats in the Least Democratic Districts

Rank District Member PVI Score
1UT-04Jim Matheson (D)R+16
2WV-03Nick Rahall (D)R+14
3NC-07Mike McIntyre (D)R+12
4GA-12John Barrow (D)R+9
5MN-07Collin Peterson (D)R+6
6AZ-01Ann Kirkpatrick (D)R+4
7AZ-02Ron Barber (D)R+3
8TX-23Pete Gallego (D)R+3
9FL-18Patrick Murphy (D)R+3
10NY-01Tim Bishop (D)R+2

The Ten Republicans in the Least Republican Districts

Rank District Member PVI Score
1CA-31Gary Miller (R)D+5
2CA-21David Valadao (R)D+2
3NJ-02Frank LoBiondo (R)D+1
4NY-19Chris Gibson (R)D+1
5CO-06Mike Coffman (R)D+1
6IL-13Rodney Davis (R)EVEN
7IA-03Tom Latham (R)EVEN
8NV-03Joe Heck (R)EVEN
9NJ-03Jon Runyan (R)R+1
10NY-02Peter King (R)R+1

The "Median District" and PVI Rankings

Another way of gauging the House is the concept of the “median district.” Because the Democratic vote tends to be more geographically concentrated in “safe” seats than the Republican vote, the median House district has always leaned slightly Republican since we introduced the Partisan Voter Index 15 years ago. In 1998, the median district was Washington’s 8th CD, then held by suburban Seattle GOP Rep. Jennifer Dunn, which was one point more Republican than the national average.

Between 2008 and 2012, the median district was Wisconsin’s 1st CD, held by none other than Rep. Paul Ryan, with a PVI score of R+2. Today, the median district is that of Washington GOP Rep. Jaime Herrera Beutler, whose 3rd CD also has a PVI score of R+2. As the Democratic vote has become even more concentrated since the mid-1990s and Republicans have used the redistricting process to shore up their own seats, the "median district" has crept rightward by nearly two points since 1998.

It's also worth noting the most Democratic and most Republican districts have grown even further apart over the years. In 1998, Rep. Charlie Rangel held the most Democratic seat in the House, NY-15 with a PVI score of D+38, and Rep. Larry Combest held the most Republican seat, TX-19 with a PVI score of R+26 - a 64 point gap. Today, Rep. Jose Serrano holds the most Democratic district, NY-15 at D+43, while Rep. Mac Thornberry holds the most Republican seat, TX-13 at R+32 - a record 75 point spread.

The Median & Most Partisan Districts, 1998-2014

PVI Vintage Most Democratic Median Seat Most Republican
1998NY-15: Rangel (D+38)WA-08: Dunn (R+1)TX-19: Combest (R+26)
2000NY-16: Serrano (D+42)CA-23: Capps (R+1)TX-19: Combest (R+29)
2002NY-16: Serrano (D+44)MI-11: McCotter (R+2)TX-08: Brady (R+28)
2004NY-16: Serrano (D+43)TX-15: Hinojosa (R+2)UT-03: Cannon (R+27)
2006NY-16: Serrano (D+43)AZ-08: Giffords (R+2)UT-03: Cannon (R+27)
2008NY-16: Serrano (D+41)WI-01: Ryan (R+2)AL-06: Bachus (R+29)
2010NY-16: Serrano (D+41)WI-01: Ryan (R+2)AL-06: Bachus (R+29)
2012NY-16: Serrano (D+41)MI-07: Walberg (R+3)TX-13: Thornberry (R+29)
2014NY-15: Serrano (D+43)WA-03: Herrera Beutler (R+2)TX-13: Thornberry (R+32)

The Ten Most Democratic Districts

Rank District Member PVI Score
1NY-15Jose Serrano (D)D+43
2NY-13Charlie Rangel (D)D+42
3PA-02Chaka Fattah (D)D+38
4CA-13Barbara Lee (D)D+37
5IL-07Danny Davis (D)D+36
6NY-05Greg Meeks (D)D+35
7NY-08Hakeem Jeffries (D)D+35
8NY-07Nydia Velazquez (D)D+34
9CA-12Nancy Pelosi (D)D+34
10FL-24Frederica Wilson (D)D+34

The Ten Most Republican Districts

Rank District Member PVI Score
1TX-13Mac Thornberry (R)R+32
2TX-11Mike Conaway (R)R+31
3GA-09Doug Collins (R)R+30
4TX-08Kevin Brady (R)R+29
5AL-06Spencer Bachus (R)R+28
6AL-04Robert Aderholt (R)R+28
7UT-03Jason Chaffetz (R)R+28
8UT-01Rob Bishop (R)R+27
9OK-03Frank Lucas (R)R+26
10LA-01Steve Scalise (R)R+26

There are also nine "Dead Center" districts with a PVI score of EVEN, notably including the Long Island 2nd District of New York Rep. Steve Israel, the chair of the Democratic Congressional Campaign Committee. Israel is safe, but many of the other eight districts are strong contenders to host competitive races in the coming years:

The Nine "Dead Center" Districts

District Member PVI Score
CA-07Ami Bera (D)EVEN
IL-12Bill Enyart (D)EVEN
IL-13Rodney Davis (R)EVEN
IA-03Tom Latham (R)EVEN
NV-03Joe Heck (R)EVEN
NY-03Steve Israel (D)EVEN
NY-18Sean Patrick Maloney (D)EVEN
NY-21Bill Owens (D)EVEN
OR-05Kurt Schrader (D)EVEN

What's Changed: The Top Trending Districts

Although a few districts' partisan orientations have remained relatively steady over the last four years, many have changed - some dramatically. The fact that 152 of 201 Democratic-held seats (76 percent) have become more Democratic and 141 of 234 Republican-held seats (60 percent) have grown more Republican suggests that conservative and liberal bastions are attracting like-minded voters. But it's not that simple; a complex mix of racial and generational change drives district-level movement.

In the top 25 Democratic-trending districts, the story is the Republican Party's increasingly poor performance with fast-growing shares of minority voters. The average white share of the population in these districts is 23 percent; in fact, none of these districts feature a white share greater than 39 percent and 16 of the 25 districts are Latino majority seats. Two are actually held be Republicans: CA-21 in California's Central Valley and FL-27 in Miami, where a huge generational divide in Cuban-American attitudes has fueled Democratic gains. CHART: The Top 25 Democratic-Trending Districts

By contrast, the average white share in the top 25 Republican-trending districts was 83 percent, and none are less than 66 percent white. All but one - AZ-04 - are in the contiguous chain of Appalachian states running from western Pennsylvania to eastern Oklahoma, and have moved against Democrats on energy issues as older, New Deal Democratic voters have exited the electorate. In the heart of Appalachia, Republican Rep. Hal Rogers' Kentucky 5th District shifted nine points, from R+16 to R+25. Just one of these districts, WV-03, is held by a Democrat.

The Top 25 Republican-Trending Districts

Rank District Member Old PVI New PVI Shift White%
1KY-05Hal Rogers (R)R+16R+25+9.4196.24%
2WV-03Nick Rahall (D)R+6R+14+8.0393.61%
3AR-01Rick Crawford (R)R+7R+14+7.1677%
4AR-04Tom Cotton (R)R+9R+15+6.3172.69%
5TN-06Diane Black (R)R+15R+21+6.2690.09%
6OK-02Markwayne Mullin (R)R+14R+20+5.7866.15%
7AL-04Robert Aderholt (R)R+23R+28+5.1584.89%
8TX-36Steve Stockman (R)R+20R+25+4.765.85%
9LA-03Charles Boustany (R)R+15R+19+4.5668.95%
10TX-04Ralph Hall (R)R+21R+25+4.5573.84%
11TN-04Scott DesJarlais (R)R+13R+18+4.4683.12%
12TN-07Marsha Blackburn (R)R+13R+18+4.3682.44%
13WV-01David McKinley (R)R+9R+14+4.3594.51%
14TN-01Phil Roe (R)R+21R+25+4.2992.49%
15MO-08VACANT (Emerson) (R)R+13R+17+4.1791.54%
16PA-09Bill Shuster (R)R+10R+14+3.7893.64%
17AZ-04Paul Gosar (R)R+16R+20+3.7475.84%
18AR-02Tim Griffin (R)R+5R+8+3.770.34%
19PA-18Tim Murphy (R)R+6R+10+3.783.21%
20VA-09Morgan Griffith (R)R+11R+15+3.790.64%
21TN-03Chuck Fleischmann (R)R+12R+16+3.793.66%
22PA-12Keith Rothfus (R)R+6R+9+3.6593.09%
23TN-02Jimmy Duncan (R)R+16R+20+3.6487.31%
24GA-09Doug Collins (R)R+27R+30+3.6379.43%
25AR-03Steve Womack (R)R+16R+19+3.6178.12%

The Top 25 Democratic-Trending Districts

Rank District Member Old PVI New PVI Shift White%
1HI-01Colleen Hanabusa (D)D+11D+18+7.4616.65%
2HI-02Tulsi Gabbard (D)D+14D+21+6.6528.84%
3CA-46Loretta Sanchez (D)D+3D+9+5.9218.43%
4GA-13David Scott (D)D+10D+16+5.8430.44%
5CA-41Mark Takano (D)D+3D+9+5.5126.010%
6CA-51Juan Vargas (D)D+11D+16+5.2314.39%
7TX-28Henry Cuellar (D)D+2D+7+5.1117.76%
8CA-21David Valadao (R)R+3D+2+4.9219.32%
9FL-09Alan Grayson (D)D+4D+8+4.8939.47%
10TX-34Filemon Vela (D)D+3D+8+4.7315.15%
11CA-35Gloria Negrete McLeod (D)D+10D+15+4.515.92%
12AZ-07Ed Pastor (D)D+12D+16+4.4120.97%
13CA-16Jim Costa (D)D+2D+7+4.3625.1%
14CA-06Doris Matsui (D)D+13D+18+4.2938.87%
15TX-15Ruben Hinojosa (D)D+1D+5+4.1816.32%
16NJ-08Albio Sires (D)D+20D+24+4.1727.82%
17TX-33Marc Veasey (D)D+14D+18+3.9614.51%
18FL-27Ileana Ros-Lehtinen (R)R+5R+2+3.917.86%
19FL-05Corinne Brown (D)D+17D+21+3.8732.07%
20CA-29Tony Cardenas (D)D+21D+25+3.7718.42%
21GA-04Hank Johnson (D)D+17D+21+3.7427.310%
22CA-32Grace Napolitano (D)D+9D+12+3.6518.11%
23TX-29Gene Green (D)D+8D+12+3.611.77%
24VA-03Bobby Scott (D)D+23D+27+3.5232.24%
25CA-09Jerry McNerney (D)D+2D+6+3.536.89%

The Cook Political Report Partisan Voter Index (PVI) Explained

In August of 1997, The Cook Political Report introduced the Partisan Voting Index (PVI) as a means of providing a more accurate picture of the competitiveness of each of the 435 congressional districts. Using the 1992 and 1996 major-party Presidential voting results, the PVI measured how each congressional district performed compared to the nation as a whole.

Using the results of the 2008 and 2012 elections for the Congressional boundaries that first took effect in 2012, we have updated these PVI scores and have even more information to draw upon to understand the congressional level trends and tilts that will help to define the elections in 2014 and beyond. We will next update PVI scores again in 2017 to reflect the results of the 2016 presidential election.

Developed for The Cook Political Report by POLIDATA®, the index is an attempt to find an objective measurement of each congressional district that allows comparisons between states and districts, thereby making it relevant in both mid-term and presidential election years.

While other data such as the results of senatorial, gubernatorial, congressional and other local races can help fine tune the exact partisan tilt of a particular district, those kinds of results don't allow a comparison of districts across state lines. Only presidential results allow for total comparability.

A Partisan Voting Index score of D+2, for example, means that in the 2008 and 2012 presidential elections, that district performed an average of two points more Democratic than the nation did as a whole, while an R+4 means the district performed four points more Republican than the national average. If a district performed within half a point of the national average in either direction, we assign it a score of EVEN.

To determine the national average for these latest ratings, we have taken the average Democratic share of the two-party presidential vote for 2008 and 2012, which is roughly 52.8 percent, and that of Republicans, which is roughly 47.2 percent. So, if Barack Obama carried 59 percent of the vote in a given district in 2008 and 57 percent in the district in 2012, the district would have a PVI score of roughly D+5.

In addition to the charts above, we have listed the PVI score for every district on the House Race At-A-Glance chart and on each individual race page. It is important to remember that redistricting in 2012 made some significant changes to the congressional map that make it hard to compare current districts with their predecessors.

Notes about PVI Data & Methodology

Following each election and round of redistricting, presidential results are compiled to generate PVI scores for each congressional district. In a few states, these results are aggregated by district by state and/or local election authorities. However, in others they are not, and the reported election results do not account for some votes that are reported centrally and not redirected back to the voter’s registration precinct.

In October 2012, Clark Bensen of Polidata offered a detailed explanation of POLIDATA's methodology for allocating these votes. Calculating presidential results by district following redistricting involves some judgment calls, and although this dataset reflects Polidata's best efforts, in rare cases raw vote data are subject to revision upon further post-election review.

Cook Political Report Web Editor Loren Fulton contributed to this report.