However, even assuming the war of 1776 was a war of independence not a "revolution" (the the colonists never sought to overthrown the government of Great Britian, only to free themselves from it's influence). The Louisana purchase is in my mind invalid having been negotiated with an illegal, revolutionary government of France, the Western US is the legal property of HM Juan Carlos of Spain and Hawaii is an occupied foreign nation.
This is all rather irrelevant tho, revolutionary government do not respect the laws of property.
But where do you stop? Speaking as a Yorkshireman wasn't Richard III illegally usurped and everything that happened since invalid?