Story Highlights 21 states solid or leaning Republican, 14 solid or leaning Democratic

GOP has maintained gains made since 2009

Wyoming is most Republican state; Vermont, Massachusetts are most Democratic

WASHINGTON, D.C. -- Republican states continue to outnumber Democratic states based on residents' party affiliation throughout 2016. Overall, Gallup classifies 21 states as solid or leaning Republican, 14 as solid or leaning Democratic, and 15 states as competitive. That seven-state GOP advantage contrasts with a 30-state Democratic advantage in 2008.

Political Composition of the 50 U.S. States Based on annual state averages of party affiliation from Gallup Daily tracking Solid Democratic Lean Democratic Competitive Lean Republican Solid Republican Net Democratic 2016 13 1 15 7 14 -7 2015 11 3 16 8 12 -6 2014 11 6 18 5 10 +2 2013 12 5 19 2 12 +3 2012 13 6 19 3 9 +7 2011 11 7 15 7 10 +1 2010 13 9 18 5 5 +12 2009 23 10 12 1 4 +28 2008 29 6 10 1 4 +30 Solid states: party has 10-point advantage; Leaning states: party has five- to nine-point advantage; Competitive states: parties within five points of each other Gallup

Although there are more Republican states, the Democratic states tend to be more populous. As a result, Democrats maintain a slight edge in party affiliation nationwide, 47% to 42%. This Democratic advantage, too, has declined considerably since 2008, one of the stronger Democratic years on record, when Democrats led 52% to 40%. That year, Republican President George W. Bush's job approval ratings hovered around 30% as the nation dealt with the worst economic problems seen in generations, while still engaged in two prolonged wars overseas.

Gallup's state party affiliation scores represent the difference between the percentage of Democrats (including Democratic-leaning independents) and Republicans (including Republican-leaning independents) in each state. Including party "leaners" in this calculation helps ensure the metric provides a good indication of each party's strength in a state, because independents who express a party leaning typically vote for that party in elections.

States in which a party has a 10-percentage-point or greater advantage in party affiliation are considered "solid" for that party. States in which a party has a five- to nine-point advantage are considered "leaning" for that party. The remaining states, those in which the percentages of Republicans and Democrats are within five percentage points of each other, are considered "competitive." The full data for all states are shown at the end of the article.

The classification of states based on their party affiliation strongly corresponds with how those states voted in the 2016 presidential election. Donald Trump won all 21 solid or leaning Republican states, while Hillary Clinton won all 14 solid or leaning Democratic states.

Trump won nine of the 15 competitive states, including Michigan, Pennsylvania, Wisconsin, North Carolina, Florida, Arizona, Georgia, Texas and Louisiana. Of those, Michigan may have been the most unlikely win for Trump, because it is the most Democratic of the competitive states, with a nearly five-point Democratic edge.

Clinton won the remaining six competitive states, including Minnesota, Maine, Virginia, Colorado, Nevada and New Hampshire. Her most unlikely win based on state party identification was in New Hampshire, which tilts Republican by four points.

The 2016 results are based on interviews with 177,778 U.S. adults conducted as part of Gallup Daily tracking. Gallup interviewed at least 500 residents in each state, including 1,000 or more in 40 states. Each state sample was weighted by the state's population characteristics to ensure it is demographically representative of the state.

Vermont, Massachusetts Most Democratic; Wyoming Most Republican State

The 10 most Republican and 10 most Democratic states have remained fairly constant across the nine years Gallup has been compiling state partisanship data regularly. Eight of the 10 most Democratic states in this year's top 10 have appeared in the top 10 all nine years Gallup has compiled data. The other two (Connecticut and Delaware) have been in the top 10 eight of the nine years.

Different states have led the list as the most Democratic state in past years, including Rhode Island, Maryland, Hawaii, New York, Massachusetts and Vermont. Vermont and Massachusetts essentially tie for first this year, with Maryland close behind.

Most Democratic States, 2016 Democratic advantage based on % Democratic/Lean Democratic minus % Republican/Lean Republican Democratic advantage pct. pts. Vermont 25.5 Massachusetts 24.9 Maryland 23.2 New York 21.1 Delaware 19.3 Hawaii 18.7 California 18.3 Connecticut 18.3 Illinois 17.9 Rhode Island 15.0 Gallup Daily

Wyoming ranks as the most Republican state this year, as it has in each of the last four years as well as in 2009 and 2010. Utah was the most Republican state the three years Wyoming was not. Idaho has also consistently finished among the top three most Republican states. Kansas is the only other state to rank in the top 10 all nine years, while North Dakota, Alabama and Montana have made the list eight of nine years. Alaska and Nebraska have each finished in the top 10 seven times, but were not among the most Republican states in 2016.

Most Republican States, 2016 Republican advantage based on % Republican/Lean Republican minus % Democratic/Lean Democratic Republican advantage pct. pts. Wyoming 33.8 Utah 27.6 Idaho 26.2 South Dakota 22.7 North Dakota 20.9 Oklahoma 17.7 Alabama 17.0 Kansas 16.9 Montana 16.1 Arkansas 14.3 Gallup Daily

Party strength shows clear regional patterns. Most of the Democratic states are in the East and on the West Coast. The strongest Republican states tend to be in the South, Mountain West and Plains states.

All Movement Since 2008 in GOP's Direction

Although the states with the strongest Democratic or strongest Republican orientations have generally stayed the same since 2008, many others states have moved from favoring one party to the other, or from favoring one party to being competitive. All of this change has been in the Republican Party's direction. Democrats' big party advantage from 2008 persisted into 2009, Barack Obama's first year as president. Over the course of Obama's presidency, however, Democrats' strength has reverted to more typical levels, both nationally and in many states.

Many states classified as Democratic in both 2008 and 2009 are now listed as competitive, if not Republican, states in both 2015 and 2016. Five other states moved from competitive to solid Republican over the same time period.

Also of note, Iowa and Ohio, two other solid Democratic states in 2008 and 2009, were categorized as lean Republican for the first time in the 2016 data. Iowa and Ohio are typically listed among key battleground states in presidential elections. Obama won both states in 2008 and 2012, but Trump won each by roughly nine percentage points in 2016.

Implications

The relative strength of each party in a state, based on its residents' party self-identification and leaning, gives a good indication of how elections will play out. The GOP recovered from two historically weak years in 2008-2009, allowing it to win a majority in the U.S. House in 2010, a Senate majority in 2014, and ultimately the presidency in 2016. The Republican Party also claims the governorship in most states and majority control of most state legislatures after strong showings in recent elections.

How well elected Republicans perform on the job will influence the relative strength of the parties both nationally and within states in the coming years. Americans' dissatisfaction with unified Republican government in George W. Bush's second term led to the Democratic Party winning control of Congress in 2006, Obama winning the presidency and Democrats expanding their congressional majorities in 2008, a majority of Americans identifying or leaning Democratic, and only five states showing clear GOP leanings.

After President Obama's first year, his job approval ratings struggled to reach majority level after he and the Democrats passed legislation to expand the government's reach in the economy, business and industry, and healthcare, all while the economy struggled to recover. Now that Republicans again have unified control of government, states that have moved in a Republican direction in recent years could just as easily move toward the Democrats if Americans are unhappy with the performance of the GOP. If, on the other hand, Americans are generally satisfied with the job President Trump and Republicans are doing, the Republican Party could hold onto its recent gains.

These data are available in Gallup Analytics.

Survey Methods Results for this Gallup poll are based on telephone interviews conducted Jan. 1-Dec. 31, 2016, on the Gallup U.S. Daily survey, with a random sample of 177,788 adults, aged 18 and older, living in all 50 U.S. states and the District of Columbia. Margins of error for individual states are no greater than ±6 percentage points and are ±3 percentage points in most states. All reported margins of sampling error include computed design effects for weighting. Each sample of national adults includes a minimum quota of 60% cellphone respondents and 40% landline respondents, with additional minimum quotas by time zone within region. Landline and cellular telephone numbers are selected using random-digit-dial methods. Learn more about how the Gallup U.S. Daily works.