National Flag Day is always the 14th day of June. National Flag Week is the week of June 14th.

The Fourth of July is traditionally celebrated as America's birthday, but the idea of an annual day specifically celebrating the Flag is believed to have first originated in 1885.

BJ Cigrand, a schoolteacher, arranged for the pupils in the Fredonia, Wisconsin Public School, to observe June 14 (the 108th anniversary of the Flag Resolution and the official adoption of The Stars and Stripes) as 'Flag Birthday'. In numerous magazines and newspaper articles and public addresses over the following years, Cigrand continued to enthusiastically advocate the observance of June 14 as 'Flag Birthday', or 'Flag Day'.

In 1894, the governor of New York directed that on June 14 the Flag be displayed on all public buildings. With BJ Cigrand and Leroy Van Horn as the moving spirits, the Illinois organization, known as the American Flag Day Association, was organized for the purpose of promoting the holding of Flag Day exercises. On June 14th, 1894, the first general public school children's celebration of Flag Day in Chicago was held in Douglas, Garfield, Humboldt, Lincoln, and Washington Parks, with more than 300,000 children participating.

Inspired by these three decades of state and local celebrations, Flag Day was officially established by the Proclamation of President Woodrow Wilson on May 30th, 1916. While Flag Day was celebrated in various communities for years after Wilson's proclamation, it was not until August 3rd, 1949, that President Truman signed an Act of Congress designating June 14th of each year as National Flag Day.