The Philadelphia Convention, now often referred to as the Constitutional Convention, was a meeting held in 1787 by delegates from the 13 states that then comprised the United States. At first, the purpose of the convention was to address the problems the federal government was having ruling the states and staying fiscally sound under the provisions of the Articles of Confederation, which had been the prevailing code for the government since 1777. What actually occurred at the Philadelphia Convention was the formation of a new plan of government, which was outlined in the newly-drafted U.S. Constitution. Created by compromises struck by delegates proposing different plans, the Constitution strengthened the federal government and remains the document which defines U.S. law to this day.
Seeking a way to deal with the problems inherent in the Articles of Confederation, the Continental Congress agreed to meet in Philadelphia at the Pennsylvania State House in May 1787. The articles were adopted in 1777 just a year after the United States declared independence from Great Britain, but they proved ineffective as the country grew. They gave little power to the federal government to regulate the action of the states, and without the ability to tax, the central government was essentially bankrupt by the mid-1880s. This left the United States vulnerable, since its ability to fund an army would have been in serious doubt if another major war had arisen.
On May 25, 1787, delegates from the 12 of the 13 states arrived and immediately elected George Washington to serve as president of the Philadelphia Convention. While the purpose of the convention was technically to address the problems of the Articles of Confederation, powerful delegates like James Madison and Alexander Hamilton saw the convention as an opportunity to draft a document that would replace the articles and strengthen the United States going forward. The delegates agreed these deliberations would be held in absolute secrecy.
Madison drafted what would become known as the Virginia Plan, a plan that proposed strengthening the role of the central government and its power to rule over the states by creating a new legislative branch in which states would be represented according to respective populations. Smaller states balked, and William Paterson of New Jersey drafted a competing plan which kept the states' rights at the forefront and simply strengthened the power of the Continental Congress. Throughout the summer of 1787, compromises were worked out between those who defended the rights of the states and those who wanted a stronger federal government.
A key element to the final document was the compromise proposed by Roger Sherman of Connecticut, which gave states equal representation in the U.S. Senate while allotting spots in the House of Representatives based on population. The delegates eventually agreed to give Congress the power to regulate the economy and national defense but preserved the integrity of state laws. On September 17, 1787, the delegates signed and ratified the U.S. Constitution to conclude the Philadelphia Convention.