A special election to the United States Senate was held in Maryland on November 4, 1913, to fill the vacancy caused by the death of Sen. Isidor Rayner. The election was the second Senate election held under the Seventeenth Amendment to the United States Constitution, which required direct popular election of senators, but was the first contested by multiple parties.

The Seventeenth Amendment to the United States Constitution established the direct election of United States senators in each state. The amendment supersedes Article I, Section 3, Clauses 1 and 2 of the Constitution, under which senators were elected by state legislatures. It also alters the procedure for filling vacancies in the Senate, allowing for state legislatures to permit their governors to make temporary appointments until a special election can be held.