Valentine greetings were popular as far back as the Middle Ages, though written Valentine’s didn’t begin to appear until after 1400. The oldest known valentine still in existence today was a poem written in 1415 by Charles, Duke of Orleans, to his wife while he was imprisoned in the Tower of London.
In addition to the United States, Valentine’s Day is celebrated in Canada, Mexico, the United Kingdom, France and Australia. In Great Britain, Valentine’s Day began to be popularly celebrated around the 17th century. By the middle of the 18th, it was common for friends and lovers of all social classes to exchange small tokens of affection or handwritten notes, and by 1900 printed cards began to replace written letters due to improvements in printing technology. Ready-made cards were an easy way for people to express their emotions at a time when direct expression of one’s feelings was discouraged.
Americans probably began exchanging hand-made valentines in the early 1700s.