Colorado was admitted to the Union on August 1, 1876 and elects U.S. senators to Senate class 2 and class 3. Both of Colorados current U.S. senators are Democrats Michael Bennet (serving since 2009) and John Hickenlooper (serving since 2021). Colorado is one of fifteen states alongside Arizona, Florida, Georgia, Hawaii, Idaho, Indiana, Louisiana, Maine, Massachusetts, Minnesota, Missouri, Nevada, South Dakota and Utah to have a younger senior senator and an older junior senator. Henry M. Teller was Colorado's longest-serving senator (1876–1882; 1885–1909).

List of senators

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