 The same year, Trowbridge was elected as a Republican from Michigan's 4th congressional district to the 37th United States Congress, serving from March 4, 1861 to March 3, 1863.After redistricting as a result of the 1860 census, Trowbridge ran as a candidate in the newly created 5th congressional district in 1862, losing to Democrat Augustus C. Baldwin.In 1864, Trowbridge defeated Baldwin to be elected to the 39th Congress, and was reelected in 1866 to the 40th Congress, serving from March 4, 1865 to March 3, 1869.