The U.S. Army was founded on 14 June 1775, when the Continental Congress authorized enlistment of expert riflemen to serve the
United Colonies for one year.

In the United States, Flag Day is celebrated on June 14. … In 1916, President Woodrow Wilson issued a proclamation that officially established June 14
as Flag Day; on August 3, 1949, National Flag Day was established by an
Act of Congress. Flag Day is not an official federal holiday.

Thomas Woodrow Wilson
(December 28, 1856 – February 3, 1924)

May Day is a public holiday usually celebrated on 1 May or the first Monday
of May. It is an ancient festival of Spring and a current traditional spring
holiday in many European cultures. Dances, singing, and cake are usually
part of the festivities.   

Every year on April 22, Earth Day marks the anniversary of the
birth of the modern environmental movement in 1970. Today
marks the 50th year.