The U. S. Constitution, which is still in force, was created by the Constitutional Convention, working behind closed doors in Philadelphia, May — September 1787. That time Philadelphia was the capital city of the Commonwealth of Pennsylvania, but not of the U. S., whereas Continental Congress was working in New York City. The article deals with a question: how the events taking place in Pennsylvania could influence the constitutional process of the U. S.? Author demonstrates that the political development of both U. S., and Pennsylvania had the same trend. In Pennsylvania the State Constitution of 1776 was in force, and there was a struggle for its remodeling, approaching success in the year 1790.