The City of Louisville (/ˈluːɪsvɪl/) is a home rule municipality located in southeastern Boulder County, Colorado, United States. The city population was 21,226 at the 2020 United States 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 a suburban residential community. CNN/Money and Money magazine have consistently listed Louisville as one of the 100 best places to live in the United States, ranking it among the top 100 in 2007, 2009 2011, 2013, 2015, and 2017.

– Updated 2022