Interstate 210 and State Route 210 (California)

The Foothill Freeway is the northernmost east-west freeway in the Los Angeles, California metropolitan area. As its name indicates, it runs along the foothills of the San Gabriel and San Bernardino mountain ranges as it passes through the San Fernando, Crescenta, and San Gabriel valleys and the Inland Empire. It is one of the principal freeways in Greater Los Angeles, serving as a major commuter route along its eastern reaches and as an attractive bypass to the congested Golden State Freeway in its western portions.

The Foothill Freeway begins in the hills separating the San Fernando and Santa Clarita valleys, above the Sylmar district of Los Angeles. From there, it heads southeast through the northeastern San Fernando Valley and the Crescenta Valley before turning straight south, then east, in Pasadena. After that, it proceeds eastward for approximately 20 miles, until the eastern edge of the city of Glendora.

Prior to 2001, the Foothill Freeway's route turned sharply south at this point, rejoining Interstate 10 along the border of San Dimas and Pomona and intersecting with the San Bernardino, Orange, and Chino Valley freeways. However, in that year, the first segment of an eastern extension of the Foothill Freeway opened; when construction is completed in 2007, the freeway will continue eastward through San Dimas and into San Bernardino County, turning southward in Highland and intersecting Interstate 10 in Redlands. As of this writing (October 2004), all of the Foothill Freeway extension but the segment between the Ontario and Escondido Freeways has been completed.

The segment of the Foothill Freeway between its western terminus near Sylmar and what is now a southern spur in Glendora is signed as Interstate 210. (The former southern spur has since been re-signed as California State Route 57 and designated as part of the Orange Freeway.) The eastern extension is signed as California State Route 210 between the southern spur and the Escondido Freeway, and as California State Route 30 from there to its eastern terminus in Redlands. Caltrans has petitioned the AASHTO, the federal body that oversees the interstate highway system, to re-sign the entire Foothill Freeway as I-210; this petition is unlikely to succeed until the eastern extension is complete.

Communities along the Foothill Freeway include:

Freeways intersected by the Foothill Freeway include:

Golden State Freeway
Ronald Reagan Freeway
Glendale Freeway
San Gabriel River Freeway
Orange Freeway
Ontario Freeway
Escondido Freeway