While some believe that Valentine's Day is celebrated in the middle of February to commemorate the anniversary of Valentine's death or burial--which probably occurred around A.D. 270--others claim that the Christian church may have decided to place St. Valentine's feast day in the middle of February in an effort to "Christianize" the pagan celebration of Lupercalia. Celebrated at the ides of February, or February 15, Lupercalia was a fertility festival dedicated to Faunus, the Roman god of agriculture, as well as to the Roman founders Romulus and Remus. 

Lupercalia survived the initial rise of Christianity and but was outlawed—as it was deemed “un-Christian”--at the end of the 5th century, when Pope Gelasius declared February 14 St. Valentine's Day. It was not until much later, however, that the day became definitively associated with love. During the Middle Ages, it was commonly believed in France and England that February 14 was the beginning of birds' mating season, which added to the idea that the middle of Valentine's Day should be a day for romance. 

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 in a time when direct expression of one's feelings was discouraged. Cheaper postage rates also contributed to an increase in the popularity of sending Valentine's Day greetings. 

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