He was elected Governor of Oregon in 1871 and served until 1877 when he resigned, having been elected to the United States Senate. Grover served from March 4, 1877, to March 3, 1883 serving in the Forty-sixth United States Congress as the chairman of the Senate Committee on Manufactures. Not a candidate for reelection in 1883, instead he resumed the practice of law and retired from public life. Grover died in Portland, Oregon, on May 10, 1911 and was interned in Riverview Cemetery. 