Since 1891, May 1 has been commemorated worldwide as International Workers Day, a day for socialists, communists, anarchists, and associated lefties to parade in the streets, light bonfires, and generally make capitalists feel nervous.
In an attempt to counterbalance the Reds, in 1958 Congress declared May 1 to be Loyalty Day, which the bill defined as "a special day for the reaffirmation of loyalty to the United States and for the recognition of the heritage of American freedom."
While the day is largely ignored by the American populace, several presidents since Eisenhower have made Loyalty Day proclamations, the most recent being Barack Obama in 2011.