"I'm confused. It's his house?" A postcard is a rectangular piece of thick paper or thin cardboard intended for writing and mailing without an envelope. Postcards were made because people were looking for an easier way to send quick notes. The Post Office was the only establishment allowed to print postcards, and it held its monopoly until May 19, 1898, when Congress passed the Private Mailing Card Act, which allowed private publishers and printers to produce postcards. Initially, the US government prohibited private companies from calling their cards "postcards", so they were known as "souvenir cards". Postcards, in the form of government postal cards and privately printed souvenir cards, became very popular as a result of the Columbian Exposition, held in Chicago in 1893, after postcards featuring buildings were distributed at the fair. In 1908, more than 677 million postcards were mailed. The postcard craze between 1907-10 was particularly popular among rural and small-town women in northern states.