Starting with the 2000 United States presidential election, the terms "red state" and "blue state" have referred to U.S. 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. 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 considerable amounts of both liberal and conservative voters (i.e., 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" was reinforced by a degree of partisan stability from election to election — from the 2000 election to the 2004 election, only three states changed "color"; and as of 2020, 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 and 2020 election. This is still a substantial difference from the period 1960 to 1980 when every state, save for Arizona, voted for each party at least once. 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. Origins of the color scheme The colors red and blue are also featured on the United States flag. Traditional political mapmakers, at least throughout the 20th century, had used blue to represent the modern-day Republicans, as well as the earlier Federalist Party. This may have been a holdover from the Civil War, during which the predominantly Republican north was considered However, at that time, a maker of widely-sold maps accompanied them with blue pencils in order to mark Confederate force movements, while red was for the union. Later, in the 1888 presidential election, Grover Cleveland and Benjamin Harrison used maps that coded blue for the Republicans, the color perceived to represent the Union and "Lincoln's Party", and red for the Democrats. The parties themselves had no official colors, with candidates variously using either or both of the national color palette of red and blue (white being unsuitable