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. I-5 then crosses into Tehama County, passing through Corning before entering Red Bluff and intersecting SR 36, which connects to the northern end of SR 99. I-5 crosses the Sacramento River twice before entering Shasta County.