Tobobo,
The 4th isn't so much a day when reenactments occur in general - though you can find some related to colonial life at historic sites such as the local one linked here http://www.fortroberdeau.org/
The Civil War reenactors are usually pretty fanatical and typically only gather on the specific sites / dates of battles. A popular one is for Picket's Charge @ Gettysburg - which took place on July 3, 1863. The proximity to July 4th is why I made mention of Gettysburg in my original email. I have been there for a reenactment some years back - they have my respect as most all wear historically accurate full uniforms, which were wool. It is usually warm and very humid (High 90's and high humidity this year) then. Gettysburg was pivotal in the war and Abraham Lincoln's Gettysburg Address which was delivered in November of that same year for the dedication of the "Soldiers National Cemetery" is a big part of American history. It is a good read - one which I wish today's politician's would refer to more often.
Some links on Gettysburg you may find interesting are below.
http://www.nps.gov/gett/index.htm
http://www.gettysburgfoundation.org/
http://www.civilwarhome.com/gettysbu.htm
http://en.wikisource.org/wiki/Gettysburg_Address
Bytor