The great Compromise
The Great Compromise of 1787 also known as the Connecticut Compromise or Sherman's Compromise, was an agreement made among the delegates to the Constitutional Convention that the American government would have two houses in Congress: the Senate where each state has two Senators and the House of Representatives where each state has a number of Representatives based on population.
The Great Compromise ended one of the most serious disagreements among the new states. Small states felt that all states were equal in stature and that if Congressional representation were based upon population, they would be outvoted on everything. Large states felt that populations should determine how many representatives a state should have, because they were afraid that they would be outvoted by the small states. This disagreement was preventing the Constitution from being adopted. In order to move forward on the Constitution, the states compromised and made Congress as a bicameral legislative body.
Two plans were put forth during the Constitutional Convention to create the new branches of government. The Virginia Plan wanted a strong national government with three branches. The legislature would have two houses. One would be directly elected by the people and the second would selected by the first house from people nominated by the state legislatures. Further, the president and national judiciary would be chosen by the national legislature. On the other hand, the New Jersey Plan wanted a more decentralized plan amending the old Articles yet allowing for a somewhat stronger government. Each state would have one vote in Congress.
The Great Compromise combined these two plans creating our current legislature with two houses, one based on population and elected by the people and the other house allowing two senators per state being appointed by state legislatures.