Classes of United States senators

A special election to fill a vacancy, usually either due to the incumbent resigning or dying while in office, may happen in any given year regardless of the seat's class.

At the same time, it provided for more frequent elections as opposed to waiting every six years, to prevent senators from permanently combining for "sinister purposes".

When the newest state, Hawaii, was admitted in 1959, its first Senate elections had candidates run either for "seat A" or "B".

The new senators, Hiram Fong and Oren E. Long, in a process managed by the Secretary of the Senate, drew lots to determine which of the two would join class 1 (whose term would end in five-and-a-half years), and which would join class 3 (whose term would end in three-and-a-half years).

Several of the most populous states, such as California, Florida, New York, Pennsylvania, and Ohio, have their senators in classes 1 and 3, provoking this imbalance.

[3] Class 1 consists of the 33 Senate seats which will be up for grabs in November 2030 and whose terms end January 3, 2031.

States with a Class 1 senator: Arizona, California, Connecticut, Delaware, Florida, Hawaii, Indiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, North Dakota, Ohio, Pennsylvania, Rhode Island, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.

Class 2 consists of the 33 Senate seats whose next election will be in November 2026 and whose terms end January 3, 2027.

States with a class 2 senator: Alabama, Alaska, Arkansas, Colorado, Delaware, Georgia, Idaho, Illinois, Iowa, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, New Hampshire, New Jersey, New Mexico, North Carolina, Oklahoma, Oregon, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Virginia, West Virginia, and Wyoming.

Class 3 consists of the 34 Senate seats whose next election will be in November 2028 and whose terms end January 3, 2029.

States with a class 3 senator: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Missouri, Nevada, New Hampshire, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Utah, Vermont, Washington, and Wisconsin.