The Federal Aid Road Act provided funds for "post roads" (significant routes in rural areas) and for "forest roads" within the boundaries of national forests. After the Washington Legislature passed the required "assenting act," the Highway Department began submitting project applications for approval.
The Pacific Highway segment approved on April 26, 1917, was a post road project. The total cost of constructing the 3.52 miles of 20-foot-wide concrete pavement was $66,883.80. Federal aid paid for $30,865.22, and the remainder came from funds credited to Thurston County in the state's Permanent Highway Fund, the Thurston County Road Fund, and the State Public Highway Fund. Work was completed in December 1917.
Thirteen other post-road projects were approved for federal aid between May 1917 and June 1918. By September 1918, grading and graveling a 3.36-mile stretch of the Olympic Highway in Mason County was also completed and work was progressing on six more projects (portions of Navy Yard Highway in Kitsap and Mason Counties, State Road No. 22 in Stevens County, and Sunset Highway in Lincoln County, and additional sections of Pacific Highway in Clark, Cowlitz, and Thurston Counties).
Work on another six approved federal aid post-road projects was deferred until 1919 or later because of war-time conditions (high prices and scarcity of labor and materials) and a United States Highway Council policy to postpone all but essential highway projects. The Highway Department also applied for federal aid for nine forest road projects, but by September 1918 only three were under way (in Okanogan and Skamania Counties and on the south shore of Lake Quinault). Several applications were rejected and work on other projects was deferred during the war.