 I-5 skirts north along the western edge of the Sacramento Valley, bypassing the larger cities of the region, including Yuba City, Oroville and Chico, before reaching Red Bluff.From Dunnigan, I-5 enters Colusa County, passing through the city of Williams and intersecting SR 20.In Glenn County, I-5 intersects SR 162 in Willows and SR 32 in Orland.