It was on Thursday, July 4th, 1776.
This depends on the year. July 21st has occurred on every day of the week.
Wednesday
Thursday
It was the day that the American Declaration of Independence from Great Britain was signed.
The day of the week the fourth of July will fall on will vary based on the year.
It was a Wednesday.
It was a Monday.
Saturday
It was a Tuesday.
Wednesday.
Sunday
Thursday