In June 1776, representatives of the 13 American colonies fighting the Revolutionary War resolved to declare their independence from Great Britain. On July 2, the Continental Congress voted yes on the idea. Two days later, the Declaration of Independence was adopted, and the break from England was official.
It's that last date—the Fourth of July—which marks America's birthday, in large part because that's the date inscribed on the Declaration of Independence.
The first observance of the Fourth of July was a year later in Philadelphia. The Congress adjourned and locals celebrated with bonfires, bells, and fireworks, according to John Adams.
The custom of celebrating America's birthday spread slowly at first, but grew in fervor at the end of the War of 1812 with Great Britain. Even so, the holiday wasn't officially established by Congress until 1870. People didn't get the day off work until 1941.
In 1826, illness forced the Declaration's author, Thomas Jefferson, to decline an invitation to come to Washington, D.C., to mark the document's 50th anniversary—though Independence Day was still nearly half a century away from holiday status. A few days prior to the celebration, he wrote:
"May it be to the world, what I believe it will be ... the signal of arousing men to burst the chains ... All eyes are opened, or opening, to the rights of man. ... For ourselves, let the annual return of this day forever refresh our recollections of these rights, and an undiminished devotion to them."
Jefferson died on that Fourth of July. John Adams, another signatory, died the same day.
The photo above by Mary L. Smith, published in the October 1917 issue of National Geographic, was accompanied by a poem that shared Jefferson's nationalistic sentiment:
Then conquer we must, when our cause it is just
And this be our motto: "In God is our trust."
And the Star Spangled Banner in triumph shall wave
O'er the land of the free and the home of the brave.