The 1916 United States Senate election in Pennsylvania was held on November 7, 1916. Incumbent Republican U.S. Senator George T. Oliver was not a candidate for re-election. The Republican nominee, Philander C. Knox defeated Democratic nominee Ellis C. Orvis.
Knox died in October 1921, during his first term,[1] and William E. Crow was appointed to fill the vacancy. Crow, however, also died before the expiration of the term, in August 1922.[2]David A. Reed was appointed to fill the vacancy created by Crow's death, and was subsequently elected to complete the rest of the term expiring in March 1923 and to a full six-year term in his own right on the same day.[3]