The U.S. Constitution was written in 1787 by 55 delegates in Philadelphia to create a stronger federal government, address problems under the Articles of Confederation, and respond to events like Shays' Rebellion. It established three branches of government with checks and balances. While some found it too powerful, others saw it as the best system to unite the states and provide order. The Constitution remains relevant today through its principles of limited government and constitutionalism, though some argue it needs updating for modern times.