William Barton Northrup was born in Belleville, Canada West on October 19, 1856 to A.G. Northrup. W.B. Northrup married twice. His first marriage occurred June, 1879 to Minnie Proctor and his second marriage occurred June, 1907 to Mary Schryrer Chemow.
He attended the Belleville Grammar School, Upper Canada College in Toronto and the University of Toronto where he received his Bachelor of Arts and Masters Degree. He was called to the Ontario Bar in 1878. He became head of the firm of Northrup and Roberts in Belleville. In 1891 he was defeated when he ran as a candidate for Hastings County, East, but at a by-election on February 20, 1892 he was elected to the House of Commons. He was defeated in 1896 and re-elected in 1900, 1904, 1908 and 1911. From March 1918 to December 1924 he was Clerk of the House of Commons. In 1902 he accompanied Prime Minister Borden on his North-West tour of Canada. He was a Conservative. He died October 22, 1925 at Ottawa, Ontario.