Republican[d] The 1888–89 United States Senate elections were held on various dates in various states, coinciding with Benjamin Harrison's victory over incumbent President Grover Cleveland.

As these U.S. Senate elections were prior to the ratification of the Seventeenth Amendment in 1913, senators were chosen by state legislatures.

Senators were elected over a wide range of time throughout 1888 and 1889, and a seat may have been filled months late or remained vacant due to legislative deadlock.

Both parties were unchanged in the regular elections, but later special elections would give Republicans an eightseat majority, mostly from newly admitted states.

Senate party division, 51st Congress (1889–1891) There were no special elections during 1888 or in 1889 before March 4.