Sunday is Flag Day, an occasion marked by flying the national colors of red, white and blue.

It celebrates the day — June 14, 1777 — that the Continental Congress meeting in Philadelphia passed a resolution specifying that the new nation’s flag carry 13 stripes and 13 stars.

It wasn’t until more than a century later, however, that the concept of a specific day to recognize the American flag each year came to be.

In 1885, a Wisconsin school teacher arranged for his students to observe “Flag Birthday” on June 14. In 1889, a New York City kindergarten teacher planned similar festivities for his pupils.

Over the subsequent decades, the community observances gathered steam. Then in 1916, President Woodrow Wilson issued a proclamation “asking for June 14 to be observed as the National Flag Day,” according to the Department of Veterans Affairs. In 1949, President Harry S. Truman signed into law an act of Congress declaring that National Flag Day be observed every June 14.

Additional sources: USflag.org, homeschooling .about.com, UShistory.org, HolidayInsights.com