State Route 52 (SR 52) is a state highway in San Diego County, California, that extends from La Jolla Parkway at Interstate 5 (I-5) in La Jolla, San Diego, to SR 67 in Santee. It is a freeway for its entire length and serves as a major east–west route through the northern part of the city of San Diego. The road connects the major north–south freeways of the county, including I-5, I-805, SR 163, I-15, SR 125, and SR 67. SR 52 passes north of the Rose Canyon Fault before traversing Marine Corps Air Station Miramar (MCAS Miramar). East of Santo Road and west of SR 125, the highway goes through Mission Trails Regional Park, a large open preserve. SR 52 is also known as the Soledad Freeway and the San Clemente Canyon Freeway. Plans for a route between La Jolla and Santee date from 1959, and SR 52 was officially designated in the 1964 state highway renumbering. Construction began in 1966 at the I-5 interchange with Ardath Road leading to La Jolla. It continued with the building of San Clemente Canyon Road, which was later widened to become SR 52. The freeway was completed east to I-805 in 1970, and was built in two stages from there to Santo Road east of I-15; the last phase was completed in 1988. The freeway east of Santo Road encountered delays from environmentalists over the endangered least Bell's vireo, a songbird which faced habitat destruction, as well as those concerned with the destruction of homes and businesses for the freeway right-of-way. The extension to Mission Gorge Road opened in 1993, and SR 52 was completed to SR 125 in 1998. Funding issues delayed the completion of the entire route until 2011, more than fifty years after construction began; until then, the city of Santee faced traffic snarls. A widening project was completed in 2007 between Santo Road and Mast Boulevard; further expansion has been put on hold due to state budget concerns. Route description SR 52 begins just west of I-5 at the eastern end of La Jolla Parkway. Before entering San Clemente Canyon, part of Marian Bear Natural Park, the road becomes a freeway as it intersects I-5. The freeway runs north of the Rose Canyon Fault, composed of Late Cretaceous rock estimated to be 90 million years old, and Mount Soledad. Following exits with Clairemont Mesa Boulevard / Regents Road