The third section of Foothill Boulevard is accessed by going south on Mountain and going east on Huntington Drive through the Los Angeles County cities of Monrovia and Duarte. Upon crossing the San Gabriel River into Irwindale, Huntington turns into Foothill Boulevard.
To reach the third segment of Foothill Boulevard, you must travel south on Mountain Avenue and then east on Huntington Drive, passing through the towns of Monrovia and Duarte. Once you cross the San Gabriel River into Irwindale, Huntington will become Foothill Boulevard.