California Code, Public Utilities Code - PUC § 90050

The area to be embraced in the district shall include all of the corporate area of each of the Cities of San Diego, Chula Vista, Coronado, National City, La Mesa, El Cajon, and Imperial Beach which establish the district as provided in this act, and any unincorporated territory in the County of San Diego contiguous thereto and being served by the San Diego Transit System, which is included in the district by the board of supervisors of the county as provided in this part.

This area shall be subdivided for the purpose of formation into two sections comprising (1) the City of San Diego and (2) the Cities of Coronado, Imperial Beach, Chula Vista, National City, El Cajon, and La Mesa and any unincorporated territories in the County of San Diego contiguous thereto and being served by the San Diego Transit System which is included in the district by the board of supervisors of the county as provided in this part.