A 1909 State Highway bond established the Redwood Highway, but construction did not begin until 1919 when a contract was let in July 1919, for construction between Gushing and Wilson Creeks in Del Norte County.

In 1923, the section from the head of Richardson Creek to Hunter Creek was built by prison labor. A camp for the prisoners was established in the Del Ponte place. By the end of 1923, the Redwood Highway, except for the bridge across the Klamath, had been completed and opened to through traffic in Del Norte and Humboldt Counties. Between Crescent City and Gushing Creek, the Redwood Highway and the old road followed the same alignment. South of Gushing Creek, the Redwood Highway clung for three miles to the cliffs, providing the motorists a spectacular view of Crescent City and the Pacific. The new highway then skirted the headwaters of Damnation Creek, descending Damnation Ridge to Wilson Creek. Its alignment here was parallel to and a few hundred yards west of the old road. Wilson Creek was crossed several hundred yards above the False Klamath.

Between Wilson and Hunter Creeks, the Redwood Highway followed the same alignment as the old road. From Hunter Creek the Redwood Highway swept towards Requa, ending at the ferry there. Once across the Klamath, the Redwood Highway wound along the coast until High Bluff, following the old road alignment in several places. From High Bluff to Orick, the alignments were identical, except at two points: between Elk Grove and May Creek, the new road was located east of the old, while at Orick the Redwood Highway crossed Redwood Creek about one half mile farther south. The California Highway Commission demonstrated at that time a keen sense of aesthetic values in accepting the right-of-way for the Redwood Highway in Del Norte and Humboldt counties.

The counties had to acquire land for the right-of-way. Heretofore, they had been in the habit of purchasing the right-of-way, logging it for profit, and then turning it over to the State Highway Commission. The State Commission now refused to go along with this practice, and the County Boards of Supervisors were required to turn over to the State an unlogged right-of-way.

In building the Redwood Highway through Del Norte and Humboldt Counties, only those redwoods interfering with construction were felled. Thousands of these giants were thus saved for the American people. This practice was followed when sections of the highway were relocated in the 1930s.