Louisville ( /luːɪsvɪl/) is a Home Rule Municipality in Boulder County, Colorado, United States. The population was 18,937 at the 2000 census. Louisville began as a rough mining community in 1877, suffered through a period of extraordinary labor violence early in the 20th century, and then, when the mines closed in the 1950s, made a transition to suburban residential community. Note that, unlike the city with a similar name in Kentucky, this city's name is pronounced "Lewis-ville" and not "Louie-ville."
The town of Louisville dates back to the start of the Welch Mine in 1877, the first coal mine in an area of Boulder and Weld counties known as the Northern Coalfield. The town was named for Louis Nawatny, a local landowner who platted his land and named it for himself. Incorporation came several years later, in 1882.
The Northern Coalfield proved to be highly productive, and eventually some 30 different mines operated within the current boundaries of Louisville, though not all at the same time. During the years of peak production (1907–09) twelve mines were in operation in Louisville, including the Acme Mine whose two million tons of coal came from directly beneath the center of town. The presence of many independent mining companies in Louisville saved the town from becoming a "company town", wholly owned and dominated by a single mining company.