The Congress of the United States is the legislative, or lawmaking, branch of the federal government. It is a bicameral legislature, which means that it is made up of two chambers, or houses. They are the House of Representatives and the Senate.

The U.S. Constitution gives the two houses similar powers. The most important of these is that no law can be adopted unless it is first passed in identical form by a majority (more than half) of the members of each house. So what makes them different, and why are there two?

The House and the Senate

There are two main reasons why the Congress has two houses. The first is in keeping with historical tradition. The framers of the Constitution were most familiar with the British Parliament, which consists of two houses. In fact, at the time of the Constitutional Convention of 1787, the legislatures of 11 of the 13 states of the United States were made up of two houses.

The second is that a bicameral (made of two houses) legislature offered a way of resolving a major conflict in the writing of the Constitution. Delegates to the Constitutional Convention from the heavily populated states wanted a state's representation in the new Congress to be based on population. Delegates from the less heavily populated states feared that the larger states would dominate the Congress if this were done. They insisted that each state receive equal representation.

This obstacle was overcome by the Great Compromise. It provided for equal representation for each state in the Senate, and for the House of Representatives to be elected on the basis of population.

Furthermore, a legislature made up of two chambers supports the system of checks and balances that is built into the American form of government. Either house is able to block legislation approved by the other. Therefore, the two houses must often cooperate with each other and compromise on their differences in writing the nation's laws.

The Big House

The House of Representatives has 435 members, or one elected from each congressional district. It is thus more than four times the size of the Senate, which has 100 members, or two elected from each state. The House of Representatives (commonly known as the House) is presided over by the Speaker of the House, who is nominated by the majority political party in that chamber. The vice president of the United States presides over the Senate.

Terms of Office

Members of the House are elected to 2-year terms of office. Senators are elected to 6-year terms. Members of the House must thus seek re-election much more frequently than senators and have to pay especially close attention to the needs and opinions of their constituents — the people in the districts they represent.

Representing You

While a senator represents an entire state, a member of the House represents a congressional district, which is usually only a small part of a state. A senator's constituency (the body of citizens he or she represents) is therefore likely to be more diverse than a House member's. For example, states have urban (city), suburban, and rural (country) areas, all of whose voters a senator must represent. A House member's district, on the other hand, may be largely urban or suburban or rural.

Special Powers

The Senate has special responsibility for the ratification, or approval, of treaties with foreign countries. The Constitution requires that "two thirds of the Senators present concur" (agree) for a treaty to be ratified. This gives the Senate more influence than the House in foreign policy matters. In addition, candidates nominated by the president for such positions as cabinet members, ambassadors, and federal judges require approval by the Senate. On the other hand, the House has a special role in tax legislation. All bills for raising revenue must originate in the House of Representatives.

Congress also has a number of other responsibilities and powers. It can propose amendments to the Constitution and declare war. The House of Representatives has the power to impeach, or bring charges against, federal officials for misconduct. If no candidate in a presidential election wins a majority in the electoral college, the president is elected by the House of Representatives. The Congress also determines if a president is disabled and thus unable to continue in office.

The Congress can conduct investigations into any matter that affects its powers under the Constitution. It also reviews the actions of federal agencies to see that programs authorized by law are carried out