Over the centuries, the holiday evolved, and by the 18th century, gift-giving and exchanging hand-made cards on Valentine's Day had become common in England. Hand-made valentine cards made of lace, ribbons, and featuring cupids and hearts eventually spread to the American colonies. The tradition of Valentine's cards did not become widespread in the United States, however, until the 1850s, when Esther A. Howland, a Mount Holyoke graduate and native of Worcester, Mass., began mass-producing them. Today, of course, the holiday has become a booming commercial success. According to the Greeting Card Association, 25% of all cards sent each year are valentines.