(NOTE: According to Wikipedia,
The holiday was first observed in 1921 as "Americanization Day," and was intended to counterbalance the celebration of Labour Day on May Day (May 1), an internationally celebrated holiday for the commemoration of the Haymarket Massacre in Chicago in 1886.
Loyalty Day is celebrated with parades and ceremonies in several U.S. communities, like Batavia, Illinois, although many people in the United States remain unaware of it. Although a legal holiday, it is not a federal holiday, and is not commonly observed.
It was made an official holiday by the U.S. Congress on July 18, 1958 (Public Law 85-529). Following the passage of this law, President Dwight D. Eisenhower proclaimed May 1, 1959 the first official observance of Loyalty Day. 
With the exception of Eisenhower in 1959 and 1960, and the years 1966 thru 1974, Loyalty day has been recognized with an official proclamation every year by every president since its inception as a legal holiday in 1958.