Why are wedding dresses white?

Queen Victoria chose white not because it symbolized purity, but because she wanted to show her people that she would run the country in an economical way. White was a much less expensive color to make than the colors typically popular for wedding dresses at the time (red, black, and purple). Plus, it gave her the option of using some lace that she already owned, rather than having something specially made.

So basically, the white dress was originally a political move.