Barstow is a city in San Bernardino County, California, United States. The population was 21,119 at the 2000 census. Barstow is a major regional transportation center. Several major highways including Interstate 15 and Interstate 40 converge in the city. It is the site of a large rail classification yard, belonging to the BNSF Railway. The Union Pacific Railroad also runs through town on trackage rights on BNSF's main line to Daggett 10 miles east, where it heads to Salt Lake City, then the BNSF heads to Chicago.