The people living in the American colonies did not like many of the actions of the British government and the taxes imposed on them.
They thought it was unfair that they would fight to take land from the natives but then had to pay rent to the King in London for it.
Increased violent protests led to war braking out in 1775.
France, Spain and the Netherlands joined the war on the side of the Americans and so the conflict became a world war against Britain.
Following many battles and around 25,000 deaths, Britain finally surrendered (gave up the fight) in 1781 after the Battle of Yorktown.
The Treaty of Paris was signed on 3rd September 1783 and the United States of America were formed and given independence from Britain.
In 1789, George Washington - who had been the commander-in-chief of the American military - was elected to be the first president of the USA.