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On May 25，1787，55 delegates from 12 states gathered in Philadelphia to revise the Articles of Confederation.In the end，after hot debate and repeated compromises，the nationalists，led by George Washington，Alexander Hamilton and James Madison，succeeded in passing an entirely new Constitution on September 17，1787，a date which has since been celebrated as Constitution Day.

The new Constitution created a strong central government，known as the federal government.In order to prevent the concentration of power，the new government was divided into three branches：the legislative，the executive and the judicial.The Constitution also instituted carefully⁃designed checks and balances to prevent any one branch from becoming too powerful.The legislative body was the Congress，which was made up of two houses：the Senate and the House of Representatives.The states were equally represented in the Senate，with each having two seats.Senators were to be chosen by the state legislature.The seats in the House were distributed according to the population of each state，with slaves counted as 3/5 of a person.The Congress had the power to pass laws，to tax，to coin money，and to regulate interstate commerce.It also had the power of approval for some personnel appointment and the power of impeachment.The executive branch was headed by the President chosen by an Electoral College whose number equaled that of the Congress.The President had the power to appoint officials，to veto legislation，and he was the commander in chief of the military.The judicial branch consisted of the Supreme Court and some lower courts.The judges were to be appointed by the President with the approval of the Senate.The Constitution provided that it would go into effect once two⁃thirds of the states ratified it.

However，there was considerable opposition to the new Constitution and the fight over ratification was fierce.Those who supported the new Constitution called themselves the Federalists and their opponents became known as the Anti⁃Federalists.The Anti⁃Federalists，led by Thomas Jefferson，criticized the new Constitution because they believed it made the central government too strong and did not provide enough guarantees for individual and state rights.They were afraid that the power of the new central government would destroy democracy.The Federalists，led by Alexander Hamilton，defended the Constitution.They wrote many pamphlets，known as the Federalist Papers，to persuade people that a strong government would be the best guarantee of liberty.In the end，the Federalists had to promise to add a Bill of Rights to the Constitution in order to persuade enough states to ratify it.By June 1788，enough states had voted for ratification and the Constitution went into effect.During the first Congress in 1791，the Bill of Rights was added to the Constitution in the form of the first ten amendments.The first nine amendments provided guarantees of individual rights which Americans have guarded very jealously ever since.These included freedom of speech，freedom of the press，the right to bear arms，and the right to a fair trial.The tenth amendment guaranteed state powers by reserving for the states all powers that were not clearly invested in the federal government by the Constitution.

The Constitution Convention

The Constitution laid down the basic principles for the American political system：division of power，protection of individual rights and private property，freedom of belief，and equality among citizens.The Constitution was by no means completely democratic.The President and the Senators were not directly elected by the people under the original terms.In addition，it allowed slavery and slave trade.However，it laid a foundation for American society that has lasted for over two hundred years.Although the country has experienced various problems and crises during that period，the Constitution has remained the basic law.