The Constitution of the United States was signed by the framers in Philadelphia on September 17, 1787 and was approved by the ninth state (as required for final ratification) on June 21, 1788. Americans came to view the Constitution as embodying the reasoned sense of the community, in no small part because the public had engaged in full, free, and extensive debates over its merits and flaws before ratifying it. Once ratified, and especially with the addition of the Bill of Rights, it became the common standard by which Americans determined the responsibilities and limits of their government. The habit of looking to the Constitution to resolve political disagreements has helped to foster and preserve a general unity among a people that is otherwise extremely diverse. The enduring relevance and applicability of the Constitution, despite two centuries of difficulties and challenges to the American experiment in self-government, is a testament to the ingenuity and foresight of its framers.