Interstate business routes are roads connecting a central or commercial district of a city or town with an Interstate bypass. These roads typically follow along local streets often along a former US route or state highway that had been replaced by an Interstate. Interstate business route reassurance markers are signed as either loops or spurs using a green shield shaped and numbered like the shield of the parent Interstate highway.
Along Interstate 10 (I-10), business routes are found in the four westernmost states through which I-10 passes: California, Arizona, New Mexico, and the far western region of Texas beyond the Pecos River. Although I-10 is a transcontinental highway, none of the states to the east along the Interstate have yet to designate I-10 business routes.
Some states regard Interstate business routes as fully integrated within their state highway system while other states consider them to be either local roads to be maintained by county or municipal authorities or a hybrid of state and local control.
Although the public may differentiate between different business routes by the number of the parent route and the location of the route, there is no uniform naming convention. Each state highway department internally uses its own designations to identify segments within its jurisdiction.
California
Interstate business routes in California are assigned by the California Department of Transportation (Caltrans), but are not maintained by Caltrans unless they overlay other routes of the state highway system. 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).
Blythe business loop
Interstate 10 Business is a business loop of I-10 at Blythe in Riverside County. The route begins at I-10 exit 236 and goes to the north along Neighbours Boulevard. The route turns to the east along Hobsonway through town, then crosses underneath I-10 just before the Colorado River at the Arizona state line and emerges from the underpass as Riviera Drive where the route reconnects with I-10 at exit 243. The business loop has major intersections with US Route 95 (US 95) and California State Route 78 (SR 78).
The route was formerly designated as part of US 60/US 70 except along Neighbours Blvd. The eastern part of the route also conveyed US 95.
Major intersections
Arizona
The business loops within Arizona are maintained by the Arizona Department of Transportation (ADOT) and by municipal authorities. I-10 has five business loops within the state including one in La Paz County, the westernmost in Arizona through which I-10 passes, and four in Cochise County, the easternmost. ADOT identifies Interstate business loops as State Business Routes followed by the number of the parent Interstate. Therefore, all I-10 business loops in Arizona carry the unsigned designation of Arizona State Route 10 Business (or State Business Route 10). Individual loops along an Interstate are designated by adding parenthetical numbers that increase eastward and northward. Gaps in numbering represent removal of former routes or potential expansion. Many of the business loops are sections of highways which preceded I-10, such as US 60, US 70, US 80 and Arizona State Route 86 (SR 86).
Quartzsite business loop
State Business Route 10 (1) (also known as SR 10 Bus.) is a business loop of I-10 at Quartzsite in La Paz County operated since 1991. The route, which follows along the local streets Quartzsite Boulevard, Main Street, and Riggles Avenue, begins at exit 17 of I-10 and US 95 west of town and ends at exit 24 of I-10 east of town. Between its termini, the route has a major intersection with SR 95 where it ends a concurrency with US 95.
The route was originally designated along part of US 60 and US 70.
Major intersections
Phoenix business loop
State Business Route 10 (Phoenix) (also known as SR 10 Bus.) was a business loop of I-10 at Phoenix, in Maricopa County, decommissioned circa 1990. Prior to the completion of I-10 through Phoenix, this business loop connected the eastern and western segments of the Interstate on a route through Downtown Phoenix.
Prior to its decommissioning, the route began at I-10 exit 142 (27th Avenue), heading south before turning east at Van Buren Street. At the five-legged intersection with Grand Avenue and 7th Avenue, I-10 BL began a concurrency with US 60 and US 89. This concurrency ended as I-10 BL turned right at 44th Street, heading south again before terminating at I-10 exit 153 (48th Street).