Adams became a railroad expert after the war, writing Chapters of Erie (1871), which exposed the corrupt financing of the Erie RR, and Railroads: Their Origin and Problems (1878).
Adams was made chairman of the government directors of the Union Pacific in 1878 and became president in 1884, but he was ousted by the forces of Jay Gould in 1890.
Adams served 24 years on the Harvard Board of Overseers and was president (18951915) of the Massachusetts Historical Society.