The US Declaration of Independence was not mostly signed on July 4th.
Why it is true
It was adopted on July 4, 1776, but the actual physical signing by the delegates mostly took place on August 2, 1776.
Source: History
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.