Preston B. Plumb (October 12, 1837 - December 20, 1891) was a United States Senator from Kansas. Born in Delaware County, Ohio, he attended a preparatory school, learned the trade of printing and afterward purchased and edited the Xenia News. He moved to Lawrence, Kansas in 1856, to support the "Free-State" movement; he was one of the founders of Emporia, Kansas where he established the Kansas News in 1857. He was secretary of the Free-State convention in 1857 and a member of the Leavenworth constitutional convention in 1859. He studied law and was admitted to the bar in 1861. He was elected to the Kansas House of Representatives in 1862 and was a reporter for the Kansas Supreme Court. During the Civil War he entered the Union Army in 1862 as second lieutenant, and served successively as captain, major, and lieutenant colonel. He was a member, of the State house of representatives in 1867 and 1868, and served as speaker in the latter year. He was prosecuting attorney of Lyon County and was president of the Emporia National Bank in 1873.
In 1877, Preston Plumb was elected as a Republican to the U.S. Senate in 1877; he was reelected in 1883 and 1888 and served from March 4, 1877, until his death. While in the Senate, he was chairman of the Committee on Public Lands (Forty-seventh through Fifty-second Congresses). He died in Washington, D.C. in 1891, and his interment was in Maplewood Cemetery, Emporia.