Foothill Boulevard starts off in Newhall Pass in the Sylmar district of Los Angeles at Sierra Highway near the southern terminus of the Antelope Valley Freeway (SR 14). Foothill Boulevard is a two-lane road through Newhall Pass, paralleling the Interstate 5 truck lanes until its intersection with Balboa Boulevard, where it becomes a four-lane road for the remainder of its length. At the I-5/I-210 interchange, Foothill Boulevard heads southeast along the Foothill Freeway, bypassing the city of San Fernando, entering Lake View Terrace south of the I-210/SR 118 interchange. SR 118 formerly ran along Foothill Boulevard from the 210/118 interchange until Pasadena. In 1974, the current alignment of Interstate 210 was completed, and the only remaining portion of the Foothill Boulevard Freeway was the unsigned freeway over the Arroyo Seco in Pasadena.