 Work on paving the Ridge Route with 20-foot (6.1 m) wide and 4-inch (100 mm) thick reinforced concrete began in 1917, but was delayed until 1919 by the U.S. entry into World War I. During work on the road, traffic was detoured via Mint and Bouquet Canyons. The road was reopened on November 15, 1919, completely paved except north of Lebec, including the grade at Grapevine, which was only oiled. After a bond issue was passed in July 1919, this portion was paved from September 1919 to May 1921; the dangerous detour included a 20 percent grade. This paving added about $ 1 million to the cost, for a total price of about $ 1.5 million (about $ 122 million in 2015), which was not paid off until 1965. Asphalt was added on top of the concrete for 20 miles (32 km) south from Swede's Cut in 1922, and in 1924 a number of dangerous blind curves were widened and straightened.
