Throughout the history of the United States Congress, some members were elected either as representatives and/or senators from more than one U.S. state at different times in their career.

Only two senators have represented more than one state.^[1]

• James Shields uniquely served terms in the US Senate for three states; representing Illinois (1849–1855), Minnesota (1858–1859), and 20 years later he was appointed by the State of Missouri for a term expiring in just six weeks (1879). He was a Democrat.^[2]
• Waitman T. Willey was a Restored Government of Virginia Senator (1861–1863) who helped create West Virginia. He was then appointed as one of the new state's first two senators (1863–1871). He was a Unionist until 1865 and a Republican thereafter.^[1]

• William Henry Harrison – the future president of the United States was a delegate to the 6th United States Congress from Northwest Territory (1799–1800), resigning to become territorial Governor of Indiana. He returned to Congress first as a representative from Ohio's 1st congressional district (1816–19), and then serving an incomplete term as senator for Ohio (1825–28), resigning to become U.S. Minister Plenipotentiary to Gran Colombia. He was a Whig.
• James M. Cavanaugh – represented Minnesota (1858–59) as a representative and then Montana Territory (1867–71) as a delegate. He was a Democrat.
• Stephen Benton Elkins – represented New Mexico Territory (1873–77) as a delegate and later West Virginia (1895–1911) as a senator. He was a Republican.
• John Noble Goodwin – represented Maine as a representative (1861–63) and later Arizona Territory as a delegate (1866–76). He was also first governor of the Territory of Arizona. He was a Republican.
• George Wallace Jones – was a delegate from Michigan Territory (1835–37) until Michigan was created as a State. He continued representing the remaining renamed Wisconsin Territory as a delegate (1837–39). Later, after Iowa was carved from the Wisconsin Territory and subsequently admitted to the union, he became one of the first senators from Iowa (1848–59). He was a Democrat.
• Richard Cunningham McCormick – represented Arizona Territory (1869–75) and later New York as a representative (1895–97). He was a Unionist as a delegate and a Republican as a representative.
• Henry Hastings Sibley – represented Wisconsin Territory (1848–49) and later Minnesota Territory as a delegate (1849–53). He was a Democrat.
• Jesse B. Thomas – represented Indiana Territory (1808–09) as a delegate and later Illinois (1818–1829) as a senator. He was initially a Democratic-Republican, but became an Anti-Jacksonian while senator.
• William H. Wallace – represented Washington Territory (1861–63) and later Idaho Territory as a delegate (1864–65). He was a Republican.