I recently came across an interesting forum on Yahoo that discussed the origins of the white wedding gown. The most popular answer to explain this trend was presented by 'Miss Beans':
'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 economic 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. '
I did a little research of my own and and looked into this question further. It appears that the white wedding dress is indeed a reliably recent tradition that was first adopted by the upper classes who were greatly influenced by news of Queen Victoria's wedding. The trend did not become widespread in the western world by the majority of brides until after World War II.
Before Victoria's wedding to Prince Albert in 1840 Royal brides did not traditionally wear white, favoring heavily brocaded and embellished gowns of bright colors, the popular choice of brides being red but not exclusively. White was an extremely rare occurrence.
As the news of Victoria and Albert's wedding spread through Europe and America, particular attention was paid to Victoria's unusual yet much decided decision to wear white. Whilst Victoria bore white to demonstrate her intent on running the country economically, it was also interpreted by most as a connotation of innocence, of sexual purity.
The elite upper classes of the western world were quick to follow in Victoria's shoes and the wearing of white wedding dresses fast becoming a symbol of purity and virginity.
The middle classes during the 19th Century were not in a position to do some quite so lavish as to wear a dress only once and so they would most commonly marry in their favorite dresses of various styles and colors.
"Married in white, you will have chosen all right." "Married in gray, you will go far away." Married in black, you will wish yourself back. Married in pearl, you'll live in a whirl. Married in green, ashamed to be seen. Married in yellow, ashamed of the fellow. Married in brown, you'll live out of town. spirits will sink. "
Since Victoria and Albert's wedding there has not been a royal wedding without the bride wearing a white dress.