By 1785, the Americans began to realize that the Articles of Confederation were too weak to become effective. The central government did not have sufficient political power to govern, the lack of a single executive resulted in a lack of leadership, the Confederation Congress could make laws but had no power to enforce them, the Congress could issue paper money and coins but had no power to buy gold and silver for backing this money and the Congress could levy taxes but had no power to collect them. There was no provision for a national court system. In order to pass a law, nine states had to agree in its favor; in order to amend the Articles, all thirteen states had to agree. Under the Articles of Confederation, the government was a confederacy in which each state retained its own political authority and the central government was responsible to the states. The control of foreign and interstate commerce was left entirely to the individual states. Chaos and confusion resulted. Consequently, in 1785, George Washington invited some representatives from Maryland and from Virginia to meet with him to discuss the problem of a stronger central government and to settle a dispute which had arisen concerning the navigation of the Potomac River. The conference started at the City Tavern (later known as Gadsby's Tavern) in Alexandria and was later continued at Mount Vernon, home of Washington. During the discussion, Washington stated that there should be a common money system for all the states as well as a common plan for regulating domestic and foreign commerce. James Madison was one of the Virginians present, and he felt that there must be other problems of common interest to all the states. Therefore, when the next General Assembly met in January 1786, Madison proposed that representatives from all the states should meet at Annapolis, Maryland on September 11, 1786 to discuss trade problems and other areas of mutual interest. The Virginia legislature, therefore, invited all the states to send representatives to Annapolis to attempt to formulate a uniform currency and commerce system for all the states. In September 1786, only five states sent delegates to the Annapolis meeting: Virginia, Delaware, New York, New Jersey and Pennsylvania. These delegates, nevertheless, suggested that a convention be held on May 25, 1787 at the State House in Philadelphia for the purpose of revising the Articles of Confederation. After this recommendation had been submitted to the Confederation Congress, it hesitatingly invited all the states to meet the next year at Philadelphia. Virginia sent seven delegates to this Philadelphia convention: George Washington, John Blair, James Madison, George Mason, James McClurg, Edmund Randolph (Governor at this time) and George Wythe.