I can't vouch for it's accuracy, but it seems that the association of red/blue with republicans/democrats was only solidified in the 2000 election. https://www.

I can't vouch for it's accuracy, but it seems that the association of red/blue with republicans/democrats was only solidified in the 2000 election. https://www.quora.com/Why-did-the-Republican-party-choose-red-the-color-of-communism https://www.quora.com/Why-did-the-Republican-party-choose-re... I'm also seeing a variety of results saying that prior to that, the incumbent party was typically shown as blue on graphics, and the challenging party was red. In 2000, those colors lined up with the current party associations (Gore being a dem like Clinton), and that election cycle was a publicized enough election that the colors stuck to the parties.