Largest sawmill in the United States opens at Potlatch. William E. Borah elected to Senate where he serves 33 years. Johnson signs with the Washington Senators. Idaho Historical Society founded. Idaho population 325,594.
Forest fires consume one-sixth of north Idaho's forests.
Idaho population 431,866. State Capitol Building completed. Idaho's first radio station, KFAU at Boise High School, goes on the air in 1922. Craters of the Moon National Monument established. Idaho population 445,032.