California State Route 125

California State Route 125

State Route 125 (SR 125) is a state highway in the US state of California that currently runs from Otay Mesa Road (former State Route 905) in Otay Mesa near the U.S.–Mexico border to State Route 52 in Santee.

The southern portion of Route 125 from Otay Mesa Road to Route 54 near Chula Vista is a toll road called the South Bay Expressway. It is California's first road built as a public/private partnership. The toll road is being funded by the private company California Transportation Ventures, Inc. and the following public agencies: the United States Department of Transportation, Caltrans, San Diego Association of Governments (SANDAG), and the City of Chula Vista.

The toll road's name is quite unusual, as it is built to freeway standards and therefore should be labeled a freeway under both California and federal law. See freeway and expressway for more information on the difference between the two.

Route 125 was originally planned to continue north through East Miramar to Poway to connect with State Route 56 and Select Arterial 680 but Poway successfully blocked that by insisting Caltrans upgrade State Route 67 instead, leaving the northern terminus at State Route 52. There still are proposals to connect it to Scripps Poway Parkway, or to extend it further north to Riverside parallel to Interstate 15, creating a third full north/south freeway for San Diego. It is currently unlikely that it will ever happen though.