He entered railway service during the summer of 1880, and during college break, he worked as a rodman on the Chicago, Burlington and Quincy Railroad.

After graduation from Lawrence Scientific School in 1881 with a degree in civil engineering, he became a clerk in the president's office of the St. Louis, Keokuk and Northwestern Railway.

On July 25, 1913, he was elected president and director of the New Haven system, succeeding Charles Sanger Mellen, and served in that position until 1917.

Elliott increased its mileage from 5,111 to 6,032 miles, and its revenue freight train load from 326 to 511 tons.

When the Chicago, Milwaukee and St. Paul built its extension to the Puget Sound right through the Northern Pacific territory, cutting severely into the competition, Elliott continued with improvements and was able to show a surplus of over $3 million in 1911 and one of over $2 million 1912.