The Town of New Castle is a home rule municipality in Garfield County, Colorado, United States.

[5] When New Castle was incorporated in 1888, its economy was largely based on mining coal that was needed by the silver-mining industry to fire silver smelters.

On February 18, 1896, a methane explosion in the Vulcan Mine killed 49 men and started a coal fire that was still burning as of 2020.

From 2000 - 2014 the population grew 129%, much higher than the average growth in Colorado over the same period (20.8%).

Interstate 70 passes by the town following the river, with access from Exit 105.