There are no business routes in Oregon as that state does not assign such designations for any of its Interstate Highways.

Local authorities may request route assignment from the Caltrans Transportation System Information Program, and all requests require approval of the executive committee of the American Association of State Highway and Transportation Officials (AASHTO).

was a business route of I-5 in San Ysidro, Chula Vista, and National City.

in Arbuckle, at 1.1 miles (1.8 km), begins at I-5 exit 566, an interchange with no northbound reentry.

The route runs seamlessly north from the offramp to Fifth Street through downtown Arbuckle, then turns west onto Freeway Underpass Road to exit 567, while Fifth Street continues north as Frontage Road (CR 99W).

in Williams begins at I-5 exit 575, runs north on Husted Road, and then northwest onto Frontage Road and Old Highway 99W, which runs along the west side of a former Southern Pacific (SP) line, now part of Union Pacific Railroad (UP).

Within downtown Williams, the route takes a reverse curve away from the tracks into Seventh Street where it intersects SR 20 Bus.

but then returns to its previous trajectory before running under a bridge for SR 20, which has one connecting road between the two routes on the northwest corner.

Entering Maxwell the road makes another slight shift away from the former SP line, but not as far away as in downtown Williams.

continues along the west side of the tracks until ending at a half diamond interchange with I-5 with only southbound offramp and northbound onramp at exit 588.

is one of the longer business loops at 20.7 miles (33.3 km) that runs between Willows and Orland, though most of the signage is as Historic Highway 99W.

The segment is merely 400 feet (120 m) from the northbound onramp[3] before turning north onto Old Highway 99W, running along the west side of the same UP line mentioned in Williams and Maxwell.

The next community is Artois, where it moves northwest further away from the old SP line than it was in Willows but still turns back north again.

The road returns to more rural setting as it enters Orland where it becomes Sixth Street and edges away from the tracks for local buildings on the east side.

The route runs along South Main Street (CR A8), on the west side of an old UP line until after the intersection with the driveway to Red Bluff Shopping Center where it curves to the northeast and crosses under a trestle for that line.

The route maintains that northeastern trajectory until just before it crosses a bridge over Reeds Creek, where the name changes to Main Street.

and westbound SR 36 has an intersection with Walnut Street (CR A7) the road that leads to Shasta College.

Less than three blocks later, the backyard of businesses along the east side is a bend in the Sacramento River, and I-5 Bus.

The routes run parallel to the former SP line again, but this time on the west side before approaching the intersection with Adobe Road.

The northern terminus of SR 36 ends where that route heads west toward Fortuna, just before the bridge over Dibble Creek.

is with Hess Road just before the route approaches the flyover interchange with I-5 at exit 651, which contains a southbound offramp and northbound onramp.

The first sites along the road are a gas station and convenience store, two motels, and a self-storage facility.

The route winds through the mountains of the southern outskirts of the city, passing by the Dunsmuir Lodge motel.

Between the intersection with Katherine and Hill streets, it runs alongside the Dunsmuir Cemetery, officially entering the city limits halfway though.

Across from the Castle Rock Water Company, Dunsmuir Avenue becomes Mott Road with a parking lot for the Hedge Creek Falls Scenic Area, while I-5 Bus.

Though primarily consisting of commercial development including motels and restaurants, a few residences can also be seen along the road.

Shortly after passing by some industrial zoning, the remnant of an even older section of US 99 can be found at Ski Village Drive.

After making a sharp curve to the west, the old section of US 99 is spotted again as Road Number 2M16, albeit cut off from I-5 Bus.

[5] The Centralia City Council was also planning to take up the issue; however, it is unclear whether a vote was held and signs were not restored to the northern half of the route.

was a section of former US 99 from Fife through Federal Way to Midway (near Des Moines) that was signed as a business loop in 1962.