State Route 259 (SR 259) is a short unsigned state highway in the U.S. state of California that serves as a freeway connector between Interstate 215 and State Route 210 in San Bernardino. It has one complete exit (Highland Avenue) and one partial exit (E Street, northbound only). Any signage along the route, Highland Avenue and E Street either mentions "To I-215 south" or "To SR 210 east", not SR 259.