Every country has their own independence day and they celebrate it from different countries. Ex: for the US it is July 4th, independence from the United Kingdom
The U.S. was originally thirteen British colonies. The American Revolutionary War was a war between these colonies and Great Britain for independence.On 4th July, 1776 the US claimed its independence...
You celebrate the day that the U.S. got it's freedom and was no longer under control of the British. Also, I think its when the U.S. became not a part of the 13 colonies anymore.