Following graduation from high school, he worked in construction in Alaska and Montana. He began his business career at age 30 in 1964, with a $30,000 loan and a single bulldozer. He created Washington Construction, which worked primarily on highway contracts and by 1969 was the largest contractor in Montana.

In the 1970s he moved into mining and dam construction. In 1986 he acquired a copper and molybdenum mine at Butte, Montana. He successfully reopened the mine and it became a very profitable operation. This success helped him diversify into railroads, marine services, coastal shipping, aviation and real estate. In 1996 Washington Construction acquired global construction and engineering company Morrison-Knudsen Corporation of Boise, Idaho, creating Washington Group International.