It got this name from a key event on July 4, 1776. On that day, a group of people agreed to a letter. It was called the Declaration of Independence. The letter was written by Thomas Jefferson. It said that the people in America had decided to form their own country. Jefferson later became our third U.S. president.
That’s why each year we celebrate this day when our country was born. You probably celebrate your own birth every year too, with a birthday. The Fourth of July is like a birthday for the whole country!