The 4th of July is Independence Day. It is the biggest national holiday in the USA. The Declaration of Independence was proclaimed in Philadelphia on July 4, 1776, when the American colonies were fighting for independence against England.
On the 11th of November there is Veteran's Day. It is I dedicated to those who fell in the two World Wars.
Thanksgiving Day is on the fourth Thursday in November. In the autumn of 1621, the Pilgrim Fathers celebrated their first harvest festival in America and called it Thanksgiving Day. Since that time it has been celebrated every year.