The CACST Transportation Programs are coordinated through the Public Transportation Program (PRT.) This program encourages the development, improvement and use of public transportation systems by operating vehicles on highways for the transportation of passengers within rural areas and small urban areas and between such areas and urbanized areas. The goal is to enhance access of rural residents to employment, health care, retail center, education, and public services. The system is known as the Rainbow Lines. Transportation is provided in colorful comfortable vans and busses. Services may be either "demand-response" or "fixed route." A taxi service called Rainbow Express is also available. Fares vary according to the "ride" requested.

The Founder's Transportation Depot constructed with TxDOT funds in Rio Grande City serves as an access point for other public transportation providers operating within the service area. The facility also provides service staff for the maintenance of the agency's vehicle fleet. The Homero T. Martinez Memorial Building provides the focus point in Hebbronville. A new transportation facility will be constructed in Zapata.