The Indian Territory and the Indian Territories are terms that generally described an evolving land area set aside by the United States Government for the relocation of Native Americans who held aboriginal title to their land as a sovereign independent state. In general, the tribes ceded land they occupied in exchange for land grants in 1803. The concept of an Indian Territory was an outcome of the US federal government's 18th- and 19th-century policy of Indian removal. After the American Civil War (18611865), the policy of the US government was one of assimilation.

The term Indian Reserve describes lands the British set aside for Indigenous tribes between the Appalachian Mountains and the Mississippi River in the time before the American Revolutionary War (17751783).

Indian Territory later came to refer to an unorganized territory whose general borders were initially set by the Nonintercourse Act of 1834, and was the successor to the remainder of the Missouri Territory after Missouri received statehood. The borders of Indian Territory were reduced in size as various Organic Acts were passed by Congress to create incorporated territories of the United States. The 1907 Oklahoma Enabling Act created the single state of Oklahoma by combining Oklahoma Territory and Indian Territory, ending the existence of an unorganized unincorporated independent Indian Territory as such. Before Oklahoma statehood, Indian Territory from 1890 onwards consisted of the Cherokee, Choctaw, Chickasaw, Creek and Seminole tribes and their territorial holdings.

Indian reservations remain within the boundaries of US states, but largely exempt from state jurisdiction. The term Indian country is used to signify lands under the control of Native nations, including Indian reservations, trust lands on Oklahoma Tribal Statistical Area, or, more casually, to describe anywhere large numbers of Native Americans live.

The United States Congress is the legislature of the federal government of the United States. It is bicameral, being composed of a lower body, the House of Representatives, and an upper body, the Senate. The Congress meets in the United States Capitol in Washington, D.C. Both senators and representatives are chosen through direct election, though vacancies in the Senate may be filled by a governor's appointment. Congress has 535 voting members: 100 senators and 435 representatives. The vice president of the United States has a vote in the Senate only when senators are evenly divided. The House of Representatives has six non-voting members.The sitting of a Congress is for a two-year term, at present, beginning every other January. Elections are held every even-numbered year on Election Day. The members of the House of Representatives are elected for the two-year term of a Congress. The Reapportionment Act of 1929 establishes that they be elected in single-member constituencies or districts by first-past-the-post and that Congressional districts be apportioned to states by population every ten years using the United States Census results, provided that each state has at least one Congressional representative. Each senator is elected at-large in their state for a six-year term, with terms staggered, so every two years approximately one-third of the Senate is up for election. Each state, regardless of population or size, has two senators, so currently, there are 100 senators for the 50 states.

Article One of the United States Constitution requires that members of Congress must be at least 25 years old (House) or at least 30 years old (Senate), have been a citizen of the United States for seven (House) or nine (Senate) years, and be an inhabitant of the state which they represent. Members in both chambers may stand for re-election an unlimited number of times.

The Congress was created by the Constitution of the United States and first met in 1789, replacing in its legislative function the Congress of the Confederation. Although not legally mandated, in practice since the 19th century, Congress members are typically affiliated with one of the two major parties, the Democratic Party or the Republican Party, and only rarely with a third party or independents affiliated with no party. In the case of the latter, the lack of affiliation with a political party does not mean that such members are unable to caucus with members of the political parties. Members can also switch parties at any time, although this is quite uncommon.