This is the World War I draft card for George Herman Ruth, known as Babe Ruth. It indicates that he worked as a baseball player, employed at Fenway Park in Boston, Massachusetts.
On May 18, 1917, Congress passed the Selective Service Act, which authorized the Federal Government to temporarily expand the military through conscription. The act eventually required all men between the ages of 21 to 45 to register for military service. Under the act, approximately 24 million men registered for the draft. Of the total U.S. troops sent to Europe, 2.8 million men had been drafted, and 2 million men had volunteered.