In the United States there is no official association between political parties and specific colours. The two major political parties use the national colours — red, white, and blue — to show their patriotism. The only common situation in which it has been necessary to assign a single colour to a party has been in the production of political maps in graphical displays of election results. In such cases, there has historically been no consistent association of particular parties with particular colours. In the weeks following the 2000 election, however, there arose the terminology of blue states and red states, in which the conservative Republican Party was associated with red and the liberal Democratic Party with blue. Political observers subsequently latched on to this association, which resulted from the use of red for Republican victories and blue for Democratic victories on the display map of a television network. This association has certainly not been consistently applied in the past: during previous presidential elections, about half of the television networks used the opposite association. In 2004, the association was mostly kept.

There is some historical use of blue for Democrats and red for Republicans — in the late 19th century and early 20th century, Texas county election boards used colour coding to help Spanish speakers and illiterates identify the parties.[2] However, this system was not applied consistently in Texas and was not picked up on a national level.

Maps for presidential elections produced by the U.S. government use the opposite system, with red for Democrats and blue for Republicans — for example, see U.S. presidential election, 1992. Nevertheless, since the 2000 election the news media have tended to use red for Republicans and blue for Democrats, especially as it relates to the electoral majority in each state, informally calling them the Red states and Blue states. The colour green is often used for the Green Party, and the colour yellow is often used for the Libertarian Party. A February 2004 article in the New York Times examined this issue.