A project to widen the two-lane road to a four-lane expressway was completed in late 2008, removing the bottleneck from the Oroville-Chico highway.

[3] State Route 149 begins at Wicks Corner as a divided highway, at an interchange with SR 70 several miles north of Oroville.

This is the north end of the State Route 70 freeway, which passes through a gap between the Campbell Hills and South Table Mountain on its way from Oroville.

The latter highway continues the corridor northwest to Chico, quickly dropping back into the Butte Creek valley.

The California Transportation Commission approved funding for four-laning SR 149 in April 1994 and the two interchanges in May 1996, with construction to begin in 1998 and cost $47 million.

Construction began in September 2005 on a new freshwater marsh near the State Route 70 intersection to replace beaver ponds in the path of the highway, and it was completed in March 2006.

[5] Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, based on the alignment that existed at the time, and do not necessarily reflect current mileage.