Red states and blue states

Starting with the 2000 United States presidential election, the terms red state and blue state have referred to US states whose voters vote predominantly for one party—the Republican Party in red states and the Democratic Party in blue states—in presidential and other statewide elections. By contrast, states where the predominant vote fluctuates between Democratic and Republican candidates are known as swing states or purple states. Examining patterns within states reveals that the reversal of the two parties' geographic bases has happened at the state level, but it is more complicated locally, with urban–rural divides associated with many of the largest changes.

All states contain both Democratic voters and Republican voters (i ., they are "purple") and only appear blue or red on the electoral map because of the winner-take-all system used by most states in the Electoral College. However, the perception of some states as "blue" and some as "red", based on plurality or majority support for either party, was reinforced by a degree of partisan stability from election to election—from the 2016 presidential election to the 2020 presidential election, only five states changed "color"; and as of 2024, 35 out of 50 states have voted for the same party in every presidential election since the red-blue terminology was popularized in 2000, with only 15 having swung between the 2000 presidential election and the 2024 election. Although many red states and blue states stay in the same category for long periods, they may also switch from blue to red or from red to blue over time.