After the war, he was a railroad regulator and executive, an author of historical works, and a member of the Massachusetts Park Commission.

[5] Adams graduated from Harvard University in 1856[6] and then studied law in the office of Richard Henry Dana Jr. and was admitted to the bar in 1858.

Adams wrote in his autobiography that he regretted having his unit reassigned since he came to the conclusion that the regiment's black soldiers were ill-suited for combat duty.

[6] On July 9, 1866, President Andrew Johnson nominated Colonel Adams for the award of the rank of brevet (honorary) brigadier general, United States Volunteers, "for distinguished gallantry and efficiency at the battles of Secessionville, South Carolina and South Mountain and Antietam, Maryland, and for meritorious services during the war" to rank from March 13, 1865, and the U. S. Senate confirmed the award on July 23, 1866.

[10][11] Adams was a Veteran Companion of the Massachusetts Commandery of the Military Order of the Loyal Legion of the United States (MOLLUS).

He saw regulation as necessary to protect investors and other businessmen from the capriciousness of a hostile public or the machinations of other unscrupulous stock jobbers.

[13] Adams had long promoted various reform ideas, as in his book Railroads, Their Origin and Problems (1878), but he had little practical experience in management.

Adams was unable to stanch the worsening financial condition of the UP, and in 1890 the railroad's owner Jay Gould forced him to resign.

[1] His writings and addresses on problems of railway management and other historical subjects frequently gave rise to widespread controversy.

In 1900, he wrote an open letter to the President of the Massachusetts Single Tax League, declaring himself a supporter of the reform Henry George had proposed, which would later be known as Georgism.

Adams represented the public on the board of arbitration in the industrial department of the National Civic Confederation in New York city, December 17, 1901.