John J. Montgomery Freeway

Interstate 5
I-5 highlighted in red
Route information
Defined by
Maintained by Caltrans
Length:	796.432 mi (1,281.733 km)
Existed:	August 7, 1947 by FHWA July 1, 1964 by Caltrans – present
Major junctions
South end:	Fed. 1 at Mexico–United States border at San Diego
	SR 15 in San Diego I-8 in San Diego I-405 in Irvine I-10 / US 101 / SR 60 in Los Angeles I-405 near Mission Hills SR 99 near Wheeler Ridge I-580 near Tracy US 50 / I-80 Bus. in Sacramento I-80 / SR 99 in Sacramento US 97 in Weed
North end:	I-5 at Oregon state line
Location
Counties:	San Diego, Orange, Los Angeles, Kern, Kings, Fresno, Merced, Stanislaus, San Joaquin, Sacramento, Yolo, Colusa, Glenn, Tehama, Shasta, Siskiyou
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future State highways in California Interstate U.S. State Pre-1964 History Unconstructed Deleted Freeway Scenic ← SR 4 US 6 →

Interstate 5 (I-5) is a major north–south route of the Interstate Highway System in the U.S. state of California. It begins at the Mexico–United States border at the San Ysidro crossing, goes north across the length of California and crosses into Oregon south of the Medford-Ashland metropolitan area. It is the more important and most used of the two major north-south routes on the Pacific Coast, the other being U.S. Route 101, which is primarily coastal.

This highway links the major California cities of San Diego, Santa Ana, Los Angeles, , Sacramento, and Redding. Among the major cities not directly linked by Interstate 5 but which are connected by local highways to it are San Francisco, Oakland and San Jose, all of which are about 80 miles (130 km) west of the highway.

Interstate 5 has several named portions: the Montgomery Freeway, San Diego Freeway, Santa Ana Freeway, Golden State Freeway, and West Side Freeway.