[3][4] New York's Adirondack Park and Alaska's Cape Krusenstern Archeological District are much larger by area, but may contain fewer contributing elements.

[3] The district's national significance relates to its long history of copper production as well as to its role in the development of the labor union movement in the United States.

As the source of nearly one-third of all the world's copper in the early 1900s,[5] Butte's mines provided one of the metals that were critical to American industrialization.

Butte itself is an urban metropolis where industrial relics such as mine yards and head frames are juxtaposed with a wide variety of residential and business structures.

Events in Butte shaped the attitudes of politicians, including Burton K. Wheeler, long-time U.S. senator from Montana.