Political party strength in U.S. states

Political parties in the United States represent groups of people who share similar ideas about how the country should be run. Each state in the country has its own set of leaders, like a governor and lawmakers, who help make decisions for the people living there.

The strength of a political party in a state shows how many of these important jobs are held by people who belong to that party. This can affect who makes laws for the state and even who gets to represent the state in the U.S. Congress.

Knowing which party is stronger in each state helps us understand how decisions are made and why certain ideas might be more popular in some places than others. It also plays a role in choosing the U.S. President, since each state’s voters have a say in who they want to represent them at the national level.

History

During much of the 1900s, some states had one political party that was much stronger than the other. In places like the southern U.S., called the "Solid South," the Democratic Party was very powerful for about 100 years, from the late 1800s all the way to the 1960s. In contrast, states in the northeastern U.S., such as Vermont, Maine, and New Hampshire, and some Midwestern states like Iowa and North Dakota, were mostly controlled by the Republican Party.

By the 1970s and 1980s, the Republican Party began to grow stronger in the southeastern U.S. as the Democratic Party's support weakened. By the 1990s, Republicans became the leading party in the southeast, even though they often had fewer members. In New England and some other states like New Jersey, New York, California, Oregon, and Connecticut, the opposite happened—the Democratic Party became stronger.

In elections for state governments in 2010, the Republican Party won more seats than the Democratic Party. After that, Republicans kept control of many state governments. By 2024, there were more states where Republicans held all top jobs, but more people lived in states where Democrats held all top jobs.

Current party strength

Another way to see which party people like more is called the Cook Partisan Voting Index (PVI). It looks at how much people in each state liked the Democratic Party or Republican Party in the last two big elections for president and compares it to the whole country.

In 2020, a study found that 31% of Americans called themselves Democrats, 25% called themselves Republicans, and 41% were not sure about either party. In 2018, there were only 10 states where people were not sure which party they liked most. Some states started to like one party more than before.

As of 2024, most people in states like California and New York liked the Democratic Party more. In states like Wyoming and Idaho, most people liked the Republican Party more. In some states, like Oregon and Rhode Island, more people did not pick either big party.

Party strength by state

Local and regional political circumstances often influence party strength.

U.S. state party control as of May 2026

See also: Government trifecta § State government trifectas

State government

Historical party strength

This section shows how different political parties have controlled state legislatures, governorships, and state governments over time.

Graphical summary

Here is a timeline showing how many states were controlled by each party from 1977 to 2026.

View source data.