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. However, following the 2022 elections, Democratic trifectas represent a majority of the national population. ==Current party strength==