Independence Day in the United States is celebrated on 4 July. It is the celebration of the anniversary of the official adoption of the Declaration of Independence. Seems simple, but as is common in the case of history, there are some interesting side notes to be mentioned.

2 July 1776
It was on this date that Congress actually voted to declare independence. So significant was this that John Adams (who was part of the committee working on the Declaration) wrote the following day to his wife Abigail Adams:

Yesterday, the greatest question was decided, which ever was debated and a greater, perhaps, never was nor will be decided among men. A resolution was passed without one dissenting colony [noder's note: New York abstained but changed to a vote of approval several days later], "that these United Colonies are, and of right ought to be, free and independent States, find as such they have, and of right ought to have, full power to make war," conclude peace, establish commerce, and to do all other acts and things which other States may rightfully do." You will see in a few days a Declaration setting forth the causes which have impelled us to this mighty revolution, and the reasons which will justify it in the sight of God and man. A plan of confederation will be taken up in a few days....

But the day is past. The second day of July, 1776, will be the most memorable epoch in the history of America. I am apt to believe that it will be celebrated by succeeding generations as the great anniversary festival. It ought to be commemorated, as the day of deliverance, by solemn acts of devotion to God Almighty. It ought to be solemnized with pomp and parade, with shows, games, sports, guns, bells, bonfires, and illuminations, from one end of this continent to the other, from this time forward, forevermore.

Of course, that's not how things turned out.

4 July 1776
Congress continued to work and revise the Declaration—some 39 additional revisions before it was officially adopted (New York delayed until 9 July). Once adopted, Congress had a printer make copies of this epochal document. There are still 24 known copies extant from this original printing. John Hancock (president of the Continental Congress) and Charles Thomson (Secretary of Congress) both signed it.

5 July 1776
They began (by order of Hancock) distributing copies to various military leaders and politicians. In particular, copies were sent to the New Jersey and Delaware legislatures.

6 July 1776
The first newspaper version appeared in the Pennsylvania Evening Post and George Washington was sent a copy.

8 July 1776
The Declaration was publicly read (for the first time) in Philadelphia. There was a celebration held.

9 July 1776
Washington had a copy read to the army in New York.

19 July 1776
Congress ordered an officially inscribed (called " engrossed") parchment copy for the members of the Continental Congress to sign.

2 August 1776
Congress actually began to sign the official copy of the Declaration. Most of the delegates signed then, some a bit later .

24 August 1776
London finally heard about the America's Declaration.

(Sources: www.icss.com/usflag/declaration.html; http://courses.smsu.edu/ftm922f/july2.htm, Adams quote; www.founding.com; www.bright.net/~jimsjems/july4.html)