From LiveScience:
The Continental Congress officially declared its freedom from British rule on July 2, 1776, the day that John Adams wrongly thought would be commemorated by future generations. July Fourth, meanwhile, marks the day Congress adopted the Declaration of Independence. As copies of the declaration spread across the colonies, celebrations kicked off. Americans lit bonfires, fired celebratory shots from their guns, rang bells, and took down symbols of the British monarchy. At that point, the Boston Tea Party and the Battles of Lexington and Concord had already happened, but the American Revolutionary War wouldn't end until the Treaty of Paris was signed in 1783.
2. Three presidents died on the Fourth of July
John Adams and Thomas Jefferson passed away within hours of each other on July 4, 1826. The two had been political rivals and then friends later in life, and both signed the Declaration of Independence. James Monroe, the nation's fifth president, was the next U.S. leader to die, and he passed away on July 4, 1831. Calvin Coolidge, the 30th president, is the only U.S. chief to have been born on the Fourth of July.
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