The Foothill Freeway is a freeway in the Los Angeles metropolitan area, California, running from the Sylmar district of Los Angeles east to Redlands. The western segment is signed as Interstate 210 (I-210) from its western end at I-5 to SR 57 in Glendora, while the eastern segment is signed as State Route 210 (SR 210) to its eastern terminus at I-10. Under the California Streets and Highways Code, the entire Foothill Freeway is legally referred to as Route 210. The Foothill Freeway name is a reference to Foothill Boulevard and the San Gabriel Mountains, both of which the freeway runs parallel to for most of its length. The freeway follows the foothills of these mountains, connecting the northeastern suburbs of Los Angeles with the Inland Empire. Historically, the Foothill Freeway spanned multiple numerical designations. Additionally, the I-210 designation has changed routings, previously including a portion of what is now the Orange Freeway (SR 57). East of Pasadena, the Foothill Freeway parallels, and in some parts replaced, the route of former U.S. Route 66. The portion between I-5 and SR 259 in San Bernardino was up to Interstate Highway standards by 2007, but the eastern segment remains signed as a state route because the portion between SR 259 and I-10 does not meet those standards. On February 26, 2020, construction to add two new lanes, one in each direction for a total of three each way, commenced. The three-year project will take place from Sterling Avenue in San Bernardino to San Bernardino Avenue in Redlands, near the eastern terminus of the highway.
