United States congressional delegations from Idaho

Since Idaho became a U.S. state in 1890, it has sent congressional delegations to the United States Senate and United States House of Representatives, beginning with the 51st United States Congress. Prior to 1890, Idaho sent non-voting delegates to the House of Representatives from 1864 to 1889. Each state elects two senators to serve for six years in general elections, with their re-election staggered. Prior to the ratification of the Seventeenth Amendment in 1913, senators were elected by the Idaho Legislature. Each state elects varying numbers of members of the House, depending on population, to two-year terms. Idaho has sent two members to the House in each congressional delegation since the 1910 United States Census.

A total of 63 unique individuals have represented Idaho in Congress; Idaho has had 26 senators and 44 representatives, and 7 have served in both the House and the Senate. Two women from Idaho, Gracie Pfost and Helen Chenoweth, have served in the House, while none have served in the Senate.

Currently, the dean, or longest-serving member of Congress from Idaho, is Mike Crapo, who was elected to the House of Representatives in 1992 and has served in Congress ever since, serving in the Senate since his election in 1998. Crapo is the second-longest serving senator in Idaho history, after William Borah.

Current delegation
Idaho's current congressional delegation in the consists of its two senators and two representatives, all of whom are Republicans. Idaho has not elected a Democratic member of Congress since Walt Minnick was elected in 2008; he was defeated by Republican Raúl Labrador two years later in 2010.

As of April 2023, the Cook Partisan Voting Index, a measure of how strongly partisan a state is, ranked both House districts and both Senate races in Idaho as solidly Republican.

Currently, the dean, or longest-serving member of Congress from Idaho, is Mike Crapo, who was elected to the House of Representatives in 1992 and has served in Congress ever since, serving in the Senate since his election in 1998. Crapo is the second-longest serving senator in Idaho history, after William Borah, and is the first member of the Church of Latter-Day Saints to serve Idaho in the Senate. Mike Simpson, who represents Idaho's 2nd congressional district, is tied with Burton L. French as the longest-serving representative from Idaho, both having been elected for thirteen terms.

United States Senate
26 people have served as a U.S. senator from Idaho, all of them men. The longest-serving senator from Idaho, William Borah, was an influential Republican legislator who eventually became the dean of the Senate during his 33 years of service. He was known for his political views independent of the Republican Party and influence on the United States Senate Committee on Foreign Relations, eventually becoming its chairman. He was instrumental in the passage of the Sixteenth and the Seventeenth Amendments, establishing the graduated income tax and popular election of Senators, respectively, but opposed the Nineteenth Amendment, which prohibited restricting the right to vote on account of sex. The last Democratic senator from Idaho was Frank Church, who similarly served for 24 years on the Foreign Relations Committee, including two years as chairman, in addition to serving as chairman of the Church Committee, whose reports helped pass the Foreign Intelligence Surveillance Act of 1978. Senator Jim McClure also rose to leadership positions, including as the chairman of the Senate Republican Conference from 1981 to 1985, and as the chairman of the United States Senate Committee on Energy and Natural Resources.

Senators are elected every six years depending on their class, with each senator serving a six-year term, and elections for senators occurring every two years, rotating through each class such that at each election, around one-third of the seats in the Senate are up for election. Idaho's senators are elected in classes II and III. Currently, Idaho is represented in the Senate by Mike Crapo and Jim Risch.

United States House of Representatives
Since the establishment of Idaho Territory, 44 people have served Idaho in the House of Representatives. Of those, only two have been women: Gracie Pfost, who served in the House from 1953 to 1962, and Helen Chenoweth, who served in the House from 1995 to 2000. No African-Americans have ever served Idaho in the House.

From 1864 to 1890, Idaho elected a non-voting delegate to the House. After statehood in 1890, the state sent one member to the House until 1913, when Idaho gained a seat in the House after the 1910 census. The representatives were elected at-large until Idaho's congressional districts were drawn in 1919. Idaho has sent two members to the House in each congressional delegation since then. One member of the House of Representatives is sent from each district via a popular vote. Districts are redrawn every ten years, after data from the US Census is collected.

1864–1890: 1 non-voting delegate
Starting on February 1, 1864, Idaho Territory sent a non-voting delegate to the House.

1890–1913: 1 seat
Following statehood on July 3, 1890, Idaho had one seat in the House.

1913–present: 2 seats
Following the 1910 census, Idaho was apportioned a second seat. It elected both seats statewide at-large on a general ticket, until 1919, when it redistricted into two districts.