The Valentine and Christmas Card were the most popular cards, followed by Christmas.
St. Patrick's Day, Easter, Halloween and Thanksgiving Cards gained popularity in the late 1800's and early 1900's.
Paper Valentines were exchanged in Europe where they were given in place of Valentine gifts. Fancy Valentines were made with real lace and ribbons, with paper lace introduced in the mid 1800's. By the end of the 1800's, Valentines were being made entirely by machine. The first commercial valentine greeting cards produced in the United States were created in the 1840s by Esther A. Howland.
Christmas cards were introduced and popularized by John Calcott Horsley, the artist of the first Christmas Card and Louis Prang, known as the Father of the Christmas Card.
Today there are Paper cards in all sizes, Singing cards, Digital Postcards, Electronic Postcards, E-cards, E-Greetings... and even Netogram's !
One that makes me laugh is the Farting chickens E-card. The website fartingchickens.com used to have an animated Happy Birthday card in which a chicken farted while blowing out the candles. How do they come up with ideas like that? and I don't think we have seen it all by now ;-) Unfortunately fartingchickens.com had to remove the card due to complaints from the Intern. Poultry Ass.