Flag Day honors a June 14, 1777, Second Continental Congress resolution about a flag for the country.
"Resolved, that the Flag of the thirteen United States shall be thirteen stripes, alternate red and white; that the Union be thirteen stars, white on a blue field, representing a new constellation," it said.
What is the history behind Flag Day?
A number of figures in the 1800s led the charge to recognize the flag's importance.
Hartford, Conn., resident George Morris in 1861 got his town "to undertake a patriotic celebration on behalf of the Union.
However, the flag was honored on June 14, 1877: "As instructed by Congress, the U.S. flag was flown from all public buildings across the country.
One of the more famous figures was Wisconsin teacher Bernard Cigrand.
He "placed a 10” 38 star flag in an inkwell and had his students write essays on what the flag meant to them," National Flag Day Foundation says online of a 1885 incident.
Cigrand would spend decades championing the flag, according to the foundation.
Another person, William Kerr, was involved in setting up the National American Flag Day Association in 1889.
U.S. presidents as part of the years he spent trying to make Flag Day be recognized.
George Bolch, a New York City principal, made his school have events in 1889, before Elizabeth Duane Gillespie fought for flags to be waved from public Philadelphia buildings in 1893.