The planning for the San Diego Trolley began in 1966 under the auspices of the Comprehensive Planning Organization (CPO), an intergovernmental agency of 13 cities and San Diego County. San Diego's streetcar system had been replaced with buses in 1949. In 1966 the local bus company, San Diego Transit, was facing a financial crisis and public takeover. The CPO developed a mass-transit plan to address the long-range transportation issues of the metropolitan area, and that plan recommended a heavy rail "rapid transit" system, similar to the BART project then under construction in the San Francisco Bay area.