The traditional white wedding gown implies maidenhood, a woman is irtuous about to get married was supposed to have yesterday.
The bridal custom of wearing white started in the XVI century but it was given a boost when Queen Victoria decided to wear a white wedding gown instead of the color wedding dresses royal brides used to wear at that time. Another monarch, Mary Queen of Scots, had worn white before when she married François II of France. However, her choice did not become popular then since white was the official color of mourning in France at the time. It is believed Mary had chosen white since she was very fond of that color and her white wedding dress surely must have highlighted her bright auburn hair and her hazel-brown eyes.
A great of women prefer to choose dark colors rather than light ones to get married in the XIX century. As dark color wedding dresses could be worn again due to economic reasons.