Membership and the U.S. Congress

Article 1 of the U.S. Constitution establishes Congress as the lawmaking body of the United States and specifies rules for its membership and the powers of each chamber. Its members are democratically elected by the American people. The U.S. Congress is a bicameral, or two-house, legislature composed of the House of Representatives and the Senate and is one of the three branches of the federal government. Each session of Congress lasts two years.

The U.S. Senate is composed of 100 members, with each state allocated two senators under the Constitution. The House of Representatives is the larger chamber, with membership for each state determined by the state's population. Total membership is now capped at 435 legislators. States with larger populations have more seats in the House; each state has a minimum of one member. The borders and size of congressional districts within a state are adjusted every 10 years in line with the most current U.S. census results. The Constitution mandates that districts within a state be approximately the same size in population. Subsequent to each census, seats in the House are reapportioned, or redistributed, according to changes in the states' populations. The drawing of district lines is carried out by state governments. Nonvoting delegates representing Washington, D.C., and the U.S. territories also have seats, as does a nonvoting resident commissioner representing Puerto Rico.

The Constitution sets very few requirements for who can serve in the House and Senate. The framers wanted Congress to be representative of the country's population. For this reason, they resisted including too many requirements, especially those involving material wealth, such as property ownership. Representatives must be at least 25 years old, have been a U.S. citizen for at least seven years, and live in the state they represent. They do not have to live in the district they represent. Senators must be at least 30 years old, have been a citizen for nine years, and live in the state they represent.

Terms in the House of Representatives are two years—thus, all seats are up for election every two years. Senate terms last six years, with staggered elections held every two years, during which one-third of Senate seats are up for election. There are no limits on the number of terms a member of Congress can serve. There are specific reasons for the difference in term lengths. The framers wished to keep members of the House regularly accountable to those they represented, instead of becoming entrenched in the insular political world of the capital city. However, longer terms in the Senate were meant to provide for stability and the development of long-term policy expertise that would guide both chambers. Originally, the two chambers differed in how they were elected; House members were chosen by popular vote, and senators were elected by state legislatures. Since the adoption of the 17th Amendment in 1913, however, senators have been popularly elected as well.

Historically, members of Congress have been predominantly white and male. The demographics of Congress changed very slowly in the second half of the 20th century and into the 21st century, although white men have continued to be overrepresented in each chamber.

Change has happened more rapidly in the House than in the Senate. The first woman to serve in the House, Jeannette Rankin of Montana, was elected in 1916; the first woman to serve in the Senate was Rebecca Felton of Georgia, who briefly served to fill a vacancy caused by a senator's death. The first woman elected to the Senate was Arkansas's Hattie Wyatt Caraway, who won election in 1932. While female House membership slowly climbed throughout the 20th century, until 1993 no more than two Senate seats were filled by women during any session of Congress. The number of women in both chambers jumped sharply that year to 47 in the House and 7 in the Senate and continued to climb, though it still remains far short of women's share of the electorate.

Racial and ethnic diversity has also experienced a slow but steady increase in Congress. While minorities made up only 6 percent of Congress in 1981, that number increased to 12 percent in 2001 and to about one in five in the 2010s.

Political scientists have identified three models of how members of Congress should represent their constituents, the people living in the district or state a member of Congress serves. Under the trustee model, legislators use their own personal and professional experience to make policy decisions they believe are best for both the country and their district or state. The trustee model does not depend on having informed citizens; in fact, members of Congress can act against the interests of the constituents if they think that would be beneficial. Under the delegate model, legislators make policy decisions based purely on what is best for their constituency. In this model, then, members of Congress have little autonomy.

As a member of Congress, a representative or senator plays three roles: legislator, party member, and servant. The third model of congressional representation reflects these three roles and the typical behavior of members of Congress. The politico model of congressional representation combines the trustee and delegate models with the impact of the influence of public opinion, interest groups, and the desire for reelection. Legislators who follow this model take into account the very influential role that public opinion, interest groups, party pressure, and the need for campaign fundraising play in their career.

Legislators are typically surrounded by a personal staff—employees who work directly for them, either in their office in the Capitol or in a district or state office. A chief of staff is usually the head of a legislator's office and is his or her closest advisor. A legislative director is in charge of all policy-related efforts, including the research work done by the member's area-focused legislative assistants. Additional staff members may include a deputy chief of staff, a press secretary, a communications director, a technology specialist, and several administrative and correspondence assistants. Members of Congress also have one or more offices in their home district or state that support and maintain the legislator's relationship with constituents. All personal staff members are separate from the committee staff members, who support the work of a congressional committee for all members.

Additionally, Congress has several legislative branch agencies that support its work, all of which are independent and nonpartisan. These agencies help gather and evaluate the enormous amount of data that supports the legislative process and provide other support functions. The Congressional Research Service (CRS) is an agency within the Library of Congress. It provides legislators with policy and legal advice and research. The Congressional Budget Office (CBO) provides legislators with cost reports and projections on current and pending legislation. It also provides reports on the president's proposed budget. The CBO is responsible for making baseline projections, based on the 10-year congressional budget, and longer-term projections. These projections help legislators make informed decisions on current and future policies. The Government Accountability Office (GAO) provides legislators with nonpartisan analysis of the efficiency of federal policies and programs. It is often called the "government watchdog." The GAO evaluates the efficiency of how federal funds are being spent. The agency audits and investigates routine and illegal activity at federal agencies and provides legislators with informed legal opinions and reports.