Catonsville () is a census-designated place (CDP) in Baltimore County, Maryland. The population was 44,701 at the 2020 US Census. The community is a streetcar suburb of Baltimore along the city's western border. The town is known for its proximity to the Patapsco River and Patapsco Valley State Park, making it a regional mountain biking hub. The town is also notable as a local hotbed of music, earning it the official nickname of "Music City, Maryland." Catonsville contains the majority of the University of Maryland, Baltimore County (UMBC), a major public research university with close to 14,000 students.