The first election that used colors to denote the two big parties in the U.S., used blue for Republicans and red for Democrats. It was after that, when Republicans started calling the Democrats "reds" for communism, that all mainstream media (the three big networks, PBS, TIME magazine, Newsweek, all big city newspapers) all at once, got on board flipping the colors to make Democrats the blue color and Republicans the red color. The Democrats were trying to separate themselves from the communists within their party and confuse the American people. That's how Republicans became the red color and Democrats became the blue color. This happened in the late 1970's when the first color graphics were widespread on network news.
The first election that used colors to denote the two big parties in the U.S., used blue for Republicans and red for Democrats. It was after that, when Republicans started calling the Democrats "reds" for communism, that all mainstream media (the three big networks, PBS, TIME magazine, Newsweek, all big city newspapers) all at once, got on board flipping the colors to make Democrats the blue color and Republicans the red color. The Democrats were trying to separate themselves from the communists within their party and confuse the American people. That's how Republicans became the red color and Democrats became the blue color. This happened in the late 1970's when the first color graphics were widespread on network news.