The earliest road to Devils Tower was a three-mile, 12 to 16-foot unpaved road with a grade of eight percent, constructed in 1917 by the National Park Service and Crook County. Visitors traveled by horse, horse-drawn buggy, and automobiles on this primitive road. Until 1928, there was no bridge across the Belle Fourche River, and visitors entering from the east had to ford the river. As the river was subject to sudden and unpredictable rises in the summer months, people often found themselves stranded in the park until water subsided. A 150-foot long steel-truss bridge (with a 150-foot wooden east approach) was finally built in 1928, only to have the east approach washed out by the river the following year. The river channel was subsequently diverted in 1930 to protect the bridge. Between 1927 and 1933, serious consideration was given to the idea of extending the entrance road to form a driving loop around Devils Tower. The earliest map to depict such a road was generated by the NPS Civil Engineering Division in August 1927. Such a road was never completed, however.
During the initial phase of Presidents Roosevelt's ''New Deal'', legislation aimed at relief and recovery provided funds for maintenance or improvement of park roads and work on the entrance road began. Some portions of the road were reconstructed on new grades and alignment during 1933 and 1934. The establishment of a Civilian Conservation Corps (CCC) camp at the monument in 1935 greatly speeded up construction developments. Several road projects were completed over the next two years, including culvert installation; construction of head walls and spillways; flattening and rounding of roadside cut and fill slopes so that they would better harmonize with the surrounding natural contours, facilitate revegetation, and minimize erosion; seeding and sodding; obliterating segments of the old roadway; moving and transplanting trees and shrubs; and installing guardrails. During 1937-1938 an oil seal coat was put on the entire road. While some roads in the national park system have been listed on the National Register as significant examples of engineering or due to their exceptional architectural features, the qualities which make the Devils Tower entrance road distinctive are related to the manner in which the road designers sought to integrate a transportation route with its natural surroundings.