The Congress of the United States has its roots in the First Continental Congress, a meeting of representatives from twelve of the thirteen British Colonies in North America, which two years later declared independence. On July 4, 1776, the Second Continental Congress adopted the Declaration of Independence, referring to the new nation as the "United States of America".
The United States Capitol
Under the Articles of Confederation, which came into effect in 1781, the Congress of the Confederation was a unicameral body with equal representation among the states in which each state had a veto over most decisions. With no executive or judicial branch, and minimal authority given to the Congress, this government was weak compared to the states. The Congress of the Confederation had authority over foreign affairs and military matters, but not to collect taxes, regulate interstate commerce, or enforce laws. States remained sovereign, and were thus free to ignore any legislation passed by Congress. This system of government led to economic troubles in the states and disputes among the states.
The ineffectiveness of the federal government under the Articles of Confederation led the Congress to summon the Convention of 1787. Originally intended to revise the Articles of Confederation, it instead wrote a completely new constitution. Virginia delegate James Madison called for a bicameral Congress in his Virginia Plan: the lower house elected directly by the people, and the upper house elected by the lower house. The smaller states, however, favored a unicameral Congress with equal representation for all states; William Paterson countered Madison's proposals with the New Jersey Plan. Eventually, a compromise was reached: the House of Representatives was to provide representation proportional by population, whereas the Senate would provide equal representation by states. To further preserve the authority of the states, it was provided that state legislatures, rather than the people, would elect senators.
The Constitution gave more powers to the federal government, such as regulating interstate commerce , managing foreign affairs and the military, and establishing a national currency. These were seen as essential for the success of the new nation and to resolve the disputes that had arisen under the Articles of Confederation, but the states retained sovereignty over other affairs. To protect against abuse of power at the federal level, the Constitution mandated separation of powers, with responsibilities divided among the executive, legislative, and judicial branches. Furthermore, the legislative body would be bicameral, so there would be checks and balances. The Constitution was ratified by the end of 1788, and its full implementation was set for March 4, 1789.