If not for the Great Depression, Kiewit might still be a local building contractor. However, because economic events forced it into new lines of work and regions by World War II, the company was ready when the time came to construct the U.S. interstate highway system. Kiewit constructed some of the most difficult and picturesque miles of America’s highway system, including sections through Arizona’s Virgin River Canyon and Colorado’s Glenwood Canyon, the Eisenhower Tunnel through the Colorado Rockies, and the Fort McHenry Tunnel beneath Baltimore Harbor.
The company built more lane-miles of the interstate highway system than any other contractor, prompting Forbes magazine to call Peter Kiewit “The Colossus of Roads.” Kiewit remains one of North America’s largest transportation contractors. After World War II, there was a renewed emphasis on the development of the western states and that meant water projects. One of Kiewit’s first post-war projects for the Bureau of Reclamation was the Friant-Kern Canal, a 152-mile project designed to supply water to agricultural lands in California’s Central Valley. The company also constructed the Monticello Dam near Sacramento, a concrete arch dam designed to feed water into the California Aqueduct.
Two of Kiewit’s most notable dam projects during this period were the concrete-arch Flaming Gorge Dam on the Green River in Utah and the earth-fill Garrison Dam on the Missouri River in North Dakota.
In the mid-1950s, United States and Canada worked together to develop the St. Lawrence Seaway. Kiewit worked on a series of seaway projects, including the Long Sault Canal and the Iroquois Dam.