The stores provided tourists with food, souvenirs, and sundries at the major attractions along Yellowstone's Grand Loop Road.

Several buildings constructed for Hamilton are significant examples of the National Park Service Rustic style of architecture and have assumed prominence as attractions in their own right.

This training helped him obtain a summer job in 1905 as an assistant to the purchasing agent for the Yellowstone Park Association at Mammoth Hot Springs.

[5] In 1916 Hamilton agreed to a 50-50 share of the automotive service concession with the Childs and opened filling stations at Old Faithful and West Thumb.

[7] In 1953 Hamilton gained control of most park concessions by purchasing stores at Mammoth Hot Springs and Canyon.

Hamilton also operated bathhouses at Old Faithful from 1933, when he bought the geyser-fed pool from Henry Brothers, until 1951 when they were demolished as inappropriate for a national park.