Reply #7: I am old enough to remember the origin of this! [View All]

[LA lady]

During U.S. national elections, media outlets commonly display election results on a map of U.S. states—with each state assigned a color based on which party's candidate won the state, as nearly all states award the sum of their electoral votes in a winner-take-all contest (the exceptions being Maine and Nebraska). Because the United States has a de facto two-party system, the national colors of red and blue came to be reserved for the two major parties.

With the adoption of color television in the 1960s (and continuing with increased use of color in newspapers in the 1980s and 1990s) media outlets took advantage of this in their electoral maps on election night. But until the 2000 election, there was no consensus on color schemes among the networks. For example, from 1972 until at least 1992, NBC consistently showed Republican-won states in blue, and Democratic-won states in red. But other networks used other patterns. ABC, in at least two presidential elections during this time, used yellow for one major party and blue for the other. However, in 2000, for the first time ever, all the major broadcast networks and all the cable news outlets utilized the same color scheme: red for Republicans and blue for Democrats.

Partly as a result of this first-time universal color-coding, the terms Red States and Blue States entered popular usage in the weeks following the 2000 presidential election. Additionally, the closeness of the disputed election kept the colored maps in the public view for longer than usual, and red and blue thus became fixed in the media and in many people's minds

It used to alternate by who was the incumbent!

http://en.wikipedia.org/wiki/Red_state_vs._blue_state_divide