The modern Christmas card industry arguably began in 1915, when a Kansas City-based fledgling postcard printing company started by Joyce Hall, later to be joined by his brothers Rollie and William, published its first holiday card. The Hall Brothers company (which, a decade later, change its name to Hallmark), soon adapted a new format for the cards—4 inches wide, 6 inches high, folded once, and inserted in an envelope.
“They discovered that people didn’t have enough room to write everything they wanted to say on a post card,” says Steve Doyal, vice president of public affairs for Hallmark, “but they didn’t want to write a whole letter."
- smithsonianmag.com (December 9, 2015)