1970 Census records list Montana's population as 694,409

1970 Several major railroads merge

1971 Chilean government takes possession of the Anaconda Company’s biggest mine (Chapter 22)

1972 Montana adopts new constitution (Chapter 21)

1973 Oil embargo helps Montana’s oil industry to boom (Chapter 21)

1973–1975 Montana passes landmark environmental laws (Chapter 21)

1975 Libby Dam completed (Chapter 20)

1975 Congress passes Indian Self-Determination and Education Assistance Act (Chapter 22)

1976 Atlantic Richfield Company (ARCO) purchases the Anaconda Company (Chapter 22)

1976 Montana establishes Equal Employment Opportunity Bureau (Chapter 21)

1979 Confederated Salish and Kootenai Tribes create the Mission Mountain Wilderness (Chapter 12)