Here at Elijah West’s tavern in Windsor, Vermont along the Connecticut River, the locals decided in July of 1777 to make this place a free and independent republic. There were a few things to iron out of course, land grants claimed by New Hampshire across the river, and claims by New York on the other side (independence from its neighbors more than independence from Great Britain was the main issue at this stage), and then this whole Revolutionary War hullabaloo. Also, a few months earlier it was decided in a preliminary vote to call the whole prospect “New Connecticut”.
Having got that out of the way, it was another decade after the Revolutionary War ended that they got around to shedding their Republic and joining the United States in 1791. Vermonters like to be sure, and they seem to have decided the USA was going to work out all right.
For more on the Constitution House, now a museum, have a look at this website.