Milton L. Amos was a farmer, rancher, and merchant in Ellsworth and Gray Counties in Kansas from 1899 through the First World War. After the war, illness forced him to retire from his Ellsworth County farm to the town of Ellsworth. Amos helped organize the Farmer's Union Cooperative movement before World War One, and served as President and Secretary-Treasurer of the Union's Ellsworth County local.

He ran unsuccessfully for the 7th District's Congressional seat in 1912 on the Socialist ticket. After his defeat by George A. Neely, Amos joined the Kansas branch of the North Dakota based National Non-Partisan League agrarian movement. He served as a National Committeeman in the years around 1920, and his work as a league organizer led Ellsworth County League opponents to threaten his life.

After the League's decline in the 1920s, Amos moved to Salina, Kansas, where' he owned and managed rental property and sold electronics equipment. He remained politically active all his life, working for the Stevenson campaign in 1956, and contributing to organizations ranging from Father Coughlin's League for Social Justice in the 1930s to Robert Oppenheimer's Emergency Committee of Atomic Scientists in the 1940s and 1950s.