When the Federal Convention met in Philadelphia in 1787 to amend the Articles of Confederation, most of the delegates agreed that the legislature should have two houses with greatly expanded powers. There was disagreement, however, over the type of representation. Heavily populated states supported James Madisonšs efforts to base representation on population alone. Delegates from smaller states supported William Patersonšs "New Jersey Plan" that would have given states equal representation in the Congress. Eventually, delegates reached a compromise that provided for a two-house legislature: one with representation based on population elected directly by the people; the other chosen by state legislatures with equal representation for each state.

On May 29, 1787, Virginia delegate Edmund Randolph proposed what became known as "The Virginia Plan." Written primarily by fellow Virginian James Madison, the plan traced the broad outlines of what would become the U.S. Constitution: a national government consisting of three branches with checks and balances to prevent the abuse of power. In its amended form, this page of Madison_s plan shows his ideas for a legislature. It describes 2 houses: one with members elected by the people for 3-year terms and the other composed of older leaders elected by the state legislatures for 7-year terms. Both would use population as a basis for dividing seats among the states.

The Constitutional Convention struggled for weeks over how representatives to a national legislature should be chosen. The report of the Grand Committee, shown here, represented an effort to find a compromise between the positions of the large and small states. On July 16, the convention adopted the "Great Compromise" based on this report. It apportioned representation in the House of Representatives by population. In the Senate, each state would be represented by two senators chosen by the state legislatures.