In California, there are four instances of Business Loop I-10 currently in existence (some better signed than others):
Pomona, Montclair, and Ontario - This was formerly Business U.S. 70-99 and was signed as Business Loop I-10 in the 1960s along Holt Boulevard. The loop begins at the Kellogg Interchange (Exit 42B to southbound California 71, then east on Holt Avenue at Exit 14 from California 71) and is supposed to extend east to Shields still remain along this route, which follows Holt Boulevard between California 71 and just east of the Ontario International Airport. Ali Pezeshkpour wrote on May 1, 2001, "The business shields are only found in Pomona, and even though I have desperately tried to find some sign that would point to a business route, I have found none on California 71 or Interstate 10. The interchanges with these freeways are not optimal, because first of all, only Westbound Interstate 10 can access Holt Boulevard, and only Eastbound Holt Boulevard can access Eastbound Interstate 10, which allows for minimum signage even for Holt Boulevard. [At] the California 71 interchange no signs are here for any loop either. The loop shields were continuous until California 71. The reason I suspect the shields are only in Pomona is because Pomona is Los Angeles County and Ontario and beyond is in San Bernardino County."
Fontana and Colton - This business route begins east of Interstate 15 and follows Valley Boulevard (former U.S. 70-99) through Colton between Exit 59 (Etiwanda Avenue/Valley Boulevard/Commerce Drive) and Exit 71 (Mount Vernon Avenue). Cameron Kaiser has photos from 2006 that verify that the loop is signed at least once on Valley Boulevard, but this business loop is not listed in the 1991 state signing log.
Indio. This business route follows Indio Boulevard along former U.S. 60-70-99, beginning at Exit 139 and returning to Interstate 10 at Exit 146 via Dillon Road. This business route is a well-preserved section of old U.S. highway through Indio as it parallels a train yard. The western part of the route is maintained by the city, the middle segment is controlled by the state, and the eastern section is maintained by the city of Coachella. At its intersection with California 111 just east of downtown (intersection of Indio Boulevard, Golf Center Parkway, and Avenue 46) is the northern terminus of California 86. California 86-111 then concurrently run south along with Business Loop I-10. The business route leaves Indio, then turns northeast at the Coachella city limits onto Dillon Road. The business loop follows Dillon Road past the California 86S expressway interchange, then rejoins Interstate 10 at Exit 146. According to the California State Highway System Signing Log (October 1991), Business Loop I-10 in Indio runs from "Interstate 10 and Indio overcrossing near Indio via Indio Boulevard and State Route 86 to Interstate 10 and Dillon Road."
Blythe. This business loop is not listed in the 1991 state signing log, but it is well-signed. The business loop begins at Exit 236, Junction California 78/Neighbors Boulevard. From Exit 236, Business Loop I-10 follows Neighbors Boulevard north briefly, then turns east onto Hobsonway, then follows Hobsonway east into downtown Blythe. The business route retuns to Interstate 10 near the Colorado River at the Riviera Drive interchange (Exit 243). To rejoin Interstate 10, the business loop follows Hobsonway to Queshan Park, then turns due south to pass under Interstate 10, and then it turns west briefly to the onramp back onto Interstate 10.
Business Loop I-10, Indio (Westbound)
Westbound Business Loop I-10 approaches the Golf Center Parkway overcrossing in Indio (the viaduct is visible in the background). This picture was taken just north of the point where California 111 splits off to the west via Avenue 46 toward Palm Springs. Golf Center Parkway itself is part of California 111, offering a connection between Interstate 10 and California 111 in Indio. Business Loop I-10 used to also be designated as California 86 (and U.S. 99 before that), before that route was truncated at the point where California 111 turns west toward Palm Springs. The features of the original U.S. 99 expressway are still prominently featured today on sections northwest of this area. Business Loop I-10 closely parallels the railroad through Indio. Photo taken 11/11/99.
Business Loop I-10, Blythe (Eastbound)
Begin Eastbound Business Loop I-10 in Blythe just north of the Interstate 10/California 78 interchange on northbound Neighbors Boulevard. Business Loop I-10 is actually heading due north at this point, but it turns due east once it reaches the old highway. Photo taken 11/10/00.
Eastbound Business Loop I-10 turns east from Neighbors Boulevard onto eastbound Hobsonway (Old U.S. 60-70) at this intersection, located just north of the Interstate 10 interchange. Photo taken 11/10/00.
Business Loop I-10, Blythe (Westbound)
End Westbound Business Loop I-10 in Blythe as it approaches Junction Interstate 10 and California 78. From this point, traffic along westbound Business Loop I-10 is defaulted onto westbound California 78 unless it takes Interstate 10 east or westbound from here. Photos taken 11/10/00.
