Political party strength in U.S. states is the level of representation of the various political parties in the United States in each statewide elective office providing legislators to the state and to the U.S. Congress and electing the executives at the state (U.S. state governor) and national (U.S. President) level.
History Throughout most of the 20th century, although the Republican and Democratic parties alternated in power at a national level, some states were so overwhelmingly dominated by one party that nomination was usually tantamount to election. This was especially true in the Solid South, where the Democratic Party was dominant for the better part of a century, from the end of Reconstruction in the late 1870s, through the period of Jim Crow Laws into the 1960s. Conversely, the rock-ribbed New England states of Vermont, Maine, and New Hampshire were dominated by the Republican Party, as were some Midwestern states like Iowa and North Dakota.
However, in the 1970s and 1980s the increasingly conservative Republican Party gradually overtook the Democrats in the southeast. The Democrats' support in the formerly Solid South had been eroded during the vast cultural, political, and economic upheaval that surrounded the 1960s. By the 1990s, the Republican Party had completed the transition into the southeast's dominant political party, despite typically having fewer members due to the prevalence of Republican voting generational Democrats. In New England, the opposite trend occurred; the former Republican strongholds of Maine and Vermont became solidly Democratic, as did formerly Republican areas of New Jersey, New York, California, Oregon, and Connecticut.
In the U.S. state legislative elections of 2010, the Republican Party held an outright majority of 3,890 seats (53% of total) compared to the Democratic party's 3,450 (47% of total) seats elected on a partisan ballot. Of the 7,382 seats in all of the state legislatures combined, independents and third parties account for only 16 members, not counting the 49 members of the Nebraska Legislature, which is the only legislature in the nation to hold non-partisan elections to determine its members. As a result of the 2010 elections, Republicans took control of an additional 20 state legislative chambers, giving them majority control of both chambers in 25 states versus the Democrats' majority control of both chambers in only 17 states, with 7 states having split or inconclusive control of both chambers (not including Nebraska). Before the 2010 elections, it was Democrats who controlled both chambers in 27 states versus the Republican party having total control in only 14 states, with 8 states divided, and Nebraska being nonpartisan.
Since this election, Republicans have maintained a majority of state legislative chambers and seats, as well as governorships nationwide. As of 2024, there are 23 Republican trifectas, 17 Democratic trifectas, and 10 divided governments with both parties holding either legislative chambers or the governorship. Additionally, the distribution of the national population living under single-party rule has shifted; approximately 41.5% of the United States population resides in a state with a Republican trifecta, 39.1% lives under a Democratic trifecta, and 19.4% lives under a divided state government.
Current party strength Cook Partisan Voting Index (PVI) Another metric measuring party preference is the Cook Partisan Voting Index (PVI). Cook PVIs are calculated by comparing a state's average Democratic Party or Republican Party share of the two-party presidential vote in the past two presidential elections to the nation's average share of the same. PVIs for the states over time can be used to show the trends of U.S. states towards, or away from, one party or the other.
Gallup On Gallup's historical trend tracking through 2025, an average of 27% of Americans identified as Democrats, 27% identified as Republicans, and 45% as Independent. Additionally, when prompted on their political leanings regardless of party affiliation, 47% of Americans identified as Democrats or leaning Democratic, while 42% identified as Republicans or leaning Republican.
In 2023, the number of competitive states according to opinion polling dropped down to 10, the lowest number since 2008. From 2023 to 2024, Wisconsin, Nevada, and Pennsylvania moved from competitive to lean Republican, while Virginia, New Mexico, and Colorado moved from competitive to lean Democratic, and Nebraska moved from lean Republican to competitive.
As of 2018, Massachusetts was the most Democratic state, with 56% of residents identifying as Democrats, while only 27% of residents identified as Republicans. Washington D.C. (while not a state) has 3 electoral votes and 76% of residents identify as Democrats, while 6% identify as Republicans. Wyoming was the most Republican state, with 59% of residents identifying as Republicans, and only 25% of residents identifying as Democrats.
+Partisan lean of U.S. adults according to Gallup pollingYearParty Identification (%)Leaned Party Identification (%)RepublicanIndependentDemocratRep / Lean RepDem / Lean Dem1991333631484419922937344249199329383441481994303832444619953039314446199630363442491997293734404919982937344149199928383441482000303534424720013235334445200233343245452003323631454520043431344548200533333343482006303434405020072839334051200828353640522009273734414920102938314445201127403145452012284031424720132542314147201426433042452015264229424520162839314247201727422942472018264230414720192841304247202029393043482021274229434620222841284544202327432745432024284328464520252745274247
Voter registration The state Democratic or Republican Party controls the governorship, the state legislative houses, and U.S. Senate representation. Nebraska's legislature is unicameral (i.e., it has only one legislative house) and is officially non-partisan, though party affiliation still has an unofficial influence on the legislative process.
The simplest measure of party strength in a state voting population is the affiliation totals from voter registration from the websites of the Secretaries of State or state Boards of Elections for the 31 jurisdictions (30 states and the District of Columbia) that allow registered voters to indicate a party preference when registering to vote. 20 states do not include party preference with voter registration. The party affiliations in the party control table are obtained from state party registration figures where indicated.For example, for earlier 2014 registration figures, see: .
As of 2026, voters in California, Delaware, Maine, Nevada, New Jersey, New Mexico, New York, and Pennsylvania are plurality-Democratic, while the majority of voters in Maryland and the District of Columbia are Democrats. Meanwhile, voters in Arizona, Florida, Louisiana, Iowa, Kansas, Kentucky, Nebraska, and West Virginia are plurality-Republican, and the majority of voters in Idaho, Oklahoma, South Dakota, Utah, and Wyoming are Republicans. In Alaska, Colorado, Connecticut, New Hampshire, North Carolina, Oregon, and Rhode Island, independent/unaffiliated voters outnumber both of the main parties. In Massachusetts, the majority of voters are independent. Ongoing trends through 2026 indicate that the total share of voters registered in either of the two major parties has dropped below 65% for the first time in over 90 years, with Democratic registration hitting an all-time low but the Republican registration is increasing.
+ Voter Registration Totals (June 2025)Party nameTotal registrants% of RegistrantsDemocratic44,900,00036.84%Republican38,000,00031.01%Independent / Unaffiliated33,700,00027.70%Other parties (combined)5,400,0004.46%Total tracked registrants122,000,000100.00%
Party strength by state Local and regional political circumstances often influence party strength.
U.S. state party control as of