Answer: Mining settlements sometimes developed into permanent towns and cities.
Explanation:
Beginning with the California Gold Rush of 1849, several other mining areas were discovered in the West.
These new boomtowns provided the crucial material for the eastern Industrial Revolution: gold, silver, zinc, copper, and lead.
Each mining area needed a town. Although most of them would disappear after the mines were emptied, leaving behind ghost towns, some of them prospered into big cities.
