The son of Swedish immigrants, James Sundquist grew up outside of Salt Lake City. After graduating from the University of Utah, he earned a master's in public administration from Syracuse University, and worked as a reporter before taking a position with the Bureau of the Budget in 1941. He worked as a speechwriter for Harry Truman, an assistant to Governor Averell Harriman, and as deputy undersecretary of agriculture in the Lyndon Johnson administration.