The U.S. Constitution was approved by the Constitutional Convention on September 17, 1787. It was to become law only if it was ratified by 9 of the 13 states. New York was a key state, but it contained strong forces opposing the Constitution. A series of 85 letters appeared in New York City newspapers between October, 1787 and August, 1788 urging support for the Constitution. These letters remain the first and most authoritative commentary on the American concept of federal government. This letter-writing campaign was conceived and orchestrated by Alexander Hamilton, the moving force behind ratification in New York. Later known as The Federalist Papers, they were published under the pseudonym 'Publius', although written by Hamilton, James Madison and John Jay.