RED STATES AND BLUE STATES....EXPLAINED!....In my post yesterday about red states and blue states, one question I pondered was this: why were Gore states colored blue in 2000 election maps and Bush states red? After all, red is traditionally the color of lefty parties around the world, and in past elections network maps had usually colored Democratic states red.

In comments, Petey provides the answer:

Since the advent of color TV, there has been a formula to avoid charges of giving any party an advantage by painting it a "better" color. Here is the formula: the color of the incumbent party alternates every 4 years.

He seems to be quite correct. The table below shows how this formula has applied since 1976:

Year	Incumbent Party	Incumbent Color	Challenger Color
1976	Republican	Blue = Ford	Red = Carter
1980	Democratic	Red = Carter	Blue = Reagan
1984	Republican	Blue = Reagan	Red = Mondale
1988	Republican	Red = Bush	Blue = Dukakis
1992	Republican	Blue = Bush	Red = Clinton
1996	Democratic	Red = Clinton	Blue = Dole
2000	Democratic	Blue = Gore	Red = Bush
2004	Republican	Red = Bush	Blue = Kerry

This fits all the available evidence, and also explains why Democrats have usually been colored red: it's a coincidence. In the six elections prior to 2000 every Democrat but one had been coded red, but that was just because of how the cycle of incumbency happened to work out during that period.

And as Petey points out in email, this raises an interesting question: what will happen in 2008? The formula will assign blue to the Republicans, but the red state/blue state divide has now become so entrenched it's hard to imagine anyone switching colors at this point. I guess in four years we'll find out just how anal the network mapping gurus really are.

POSTSCRIPT: If anyone has firsthand knowledge — or knows someone with firsthand knowledge — about when this formula was agreed on and how it came about, please email me. It would be interesting to nail this down once and for all.