Business routes of Interstate 8

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Interstate 8 Business

CountryUnited States
Highway system

There are five business routes of Interstate 8 (I-8).

The portions of the I-8 business routes through California are mostly unsigned. All 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).[1]

El Cajon loop

Interstate 8 Business

LocationEl Cajon, California to Lakeside, California
Length8.15 mi[2] (13.12 km)

Business Loop 8 (I-8 Bus.) begins as El Cajon Boulevard at an interchange with I-8, loosely paralleling the freeway on the northern side. The loop passes through Bostonia and Lakeview before ending at the Lake Jennings Park Road interchange with I-8.[2]

Major intersections
The entire route is in San Diego County.

El Cajon0.000.00
I-8 west (Mission Valley Freeway)
Western terminus; I-8 exit 15; no access to I-8 east
Chase Avenue / Boulevard PlacePartial interchange eastbound, at-grade intersections westbound

I-8 east (Mission Valley Freeway)
I-8 west exit 20A; no access to I-8 west
I-8 – San Diego, El CentroEastern terminus; road continues south as Lake Jennings Park Road
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

Alpine loop

Interstate 8 Business

LocationAlpine, California

Business Loop 8 (I-8 Bus.) in Alpine spanned from I-8 exit 30 to exit 33 and was mostly former US 80 along Alpine Drive.

El Centro loop

Interstate 8 Business

LocationEl Centro, California
Length4.25 mi[3] (6.84 km)

Business Loop Interstate 8 (I-8 Bus.) is a business loop route that diverges from I-8 in El Centro, California, to pass through the downtown area. I-8 Bus. originates and terminates with I-8 and acts as a direct link to El Centro as I-8 bypasses the downtown area.

The I-8 Bus. path through El Centro traces roughly three sides of a rectangle with I-8 constituting the fourth side. I-8 Bus. begins at its western terminus with I-8 by going north along Imperial Avenue. When I-8 Bus. reaches the intersection of Adams Avenue it turns east along that road. Along this stretch, I-8 Bus. is joined by State Route 86 (SR 86) which approaches from the north along Imperial Avenue, and by Imperial County Route S80 which approaches from the west along Adams Avenue. The three routes continue joined as Adams Avenue ends and turns south along Fourth Avenue where S80 then turns to continue east. I-8 Bus. and SR 86 continue south running concurrent until I-8 Bus. reaches its eastern terminus with I-8.[3]

Only the portion of I-8 Bus. that runs concurrently with SR 86 is maintained by the state.[4] Along its concurrency with SR 86, I-8 Bus. is designated as part of the Juan Bautista de Anza National Historic Trail.[5]

Major intersections
The entire route is in El Centro, Imperial County.

I-8 (Kumeyaay Highway) – San Diego, YumaWestern terminus; I-8 exit 114

SR 86 north (Imperial Avenue north) / CR S80 west (Adams Avenue west) – Brawley, Los Angeles
Western end of SR 86/CR S80 concurrency; former US 99 north/US 80 west
CR S80 east (Main Street) – Holtville
Eastern end of CR S80 concurrency; former US 80 east

I-8 (Kumeyaay Highway) / SR 86 south (4th Street south) – San Diego, Yuma
Eastern terminus; eastern end of SR 86 concurrency; former US 99 south; I-8 exit 115
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

Winterhaven–Yuma loop

Interstate 8 Business
State Business Route 8 (1)

LocationWinterhaven, CaliforniaYuma, Arizona
Length14.84 mi[6][7]:531 (23.88 km)
A map of the Winterhaven–Yuma business loop. The route is highlighted in red.

Business Loop 8 (I-8 Bus. or I-8 BL) begins at an interchange with I-8 and Winterhaven Drive in Winterhaven, California. The loop continues east, paralleling I-8 to the north and running concurrently with CR S24. I-8 Bus. then goes through downtown Winterhaven before CR S24 continues east and I-8 Bus. continues south, crossing I-8 again as well as the Colorado River into Yuma, Arizona. Passing to the west of Yuma Quartermaster Depot State Historic Park, I-8 BL goes through downtown Yuma as Fourth Avenue, intersecting US 95 after several blocks. The business loop curves to the east as 32nd Street, passing along the north side of Yuma International Airport and the south side of the Yuma Conservation Garden. East of the airport, I-8 BL passes through less-developed areas of eastern Yuma before ending at I-8.[6]

It is one of very few Interstate business loops that is interstate in the sense of crossing a state line. The Arizona segment of the business loop is also a section of Historic US 80.[9]

Major intersections

CaliforniaImperial0.000.00 I-8 – El Centro, YumaWestern terminus; I-8 exit 170
CR S24 west (Araz Road)
Western end of CR S24 concurrency; former US 80 west
CR S24 east (Picacho Road)
Eastern end of CR S24 concurrency; former US 80 east
2.013.23 I-8 – San DiegoI-8 exit 172
Colorado River2.18
California–Arizona state line
Historic US 80 west (1st Street)
Western end of Historic US 80 concurrency
US 95 (16th Street) to I-8 – Quartzsite, San Luis

SR 195 south (Araby Road) to I-8

I-8 / Historic US 80 ends
Eastern terminus; eastern end of Historic US 80 concurrency, road continues as Frontage Road; I-8 exit 9
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

Gila Bend loop

State Business Route 8 (3)

LocationGila Bend, Arizona
Length5.96 mi[7]:535 (9.59 km)
A map of the Gila Bend business loop. The route is highlighted in red.

State Business Route 8 (3) (also known as SR 8 Bus.) begins at an interchange with I-8 west of Gila Bend before passing under the freeway, continuing east and merging with SR 85 at a truck stop. As Pima Street, the two highways continue through downtown Gila Bend before I-8 BL turns south away from SR 85 as Butterfield Trail and ending at I-8 at a diamond interchange.[11]

Major intersections

The entire route is in Maricopa County.

Gila Bend117.28–

I-8 / Historic US 80 begins / Frontage Road – San Diego
Western terminus; westbound entrance and eastbound exit; western terminus of Historic US 80; I-8 exit 115

SR 85 south to I-8 east – Ajo, Mexico
Western end of SR 85 concurrency
Historic US 80 east (Old Highway 80)
Eastern end of Historic US 80 concurrency; former US 80 east

SR 85 north (Pima Street) to I-10 – Phoenix, Los Angeles
Eastern end of SR 85 concurrency

I-8 to I-10 – Tucson
Eastern terminus; I-8 exit 119
1.000 mi = 1.609 km; 1.000 km = 0.621 mi


  1. ^ Division of Design (May 7, 2012). "Highway Design Manual, Chapter 20, Index 21.2" (PDF). California Department of Transportation. p. 3. Retrieved September 9, 2014.
  2. ^ a b c Google (November 2, 2014). "El Cajon Boulevard" (Map). Google Maps. Google. Retrieved November 2, 2014.
  3. ^ a b c Google (February 16, 2008). "Overview Map of I-8 in California" (Map). Google Maps. Google. Retrieved February 16, 2008.
  4. ^ California Department of Transportation (July 2007). "Log of Bridges on State Highways". Sacramento: California Department of Transportation.
  5. ^ "Juan Bautista de Anza National Historic Trail Guide: Imperial County". National Park Service. Retrieved October 6, 2008.
  6. ^ a b c Google (December 9, 2017). "Overview of Business Loop I-8 Winterhaven-Yuma" (Map). Google Maps. Google. Retrieved December 9, 2017.
  7. ^ a b c d Arizona Department of Transportation. "2013 ADOT Highway Log" (PDF). pp. 531–533. Retrieved December 9, 2017.
  8. ^ Arizona Department of Transportation. "ADOT Right-of-Way Resolution 1966-P-075". Arizona Department of Transportation. Retrieved October 18, 2018.
  9. ^ a b c Arizona State Transportation Board Meeting Agenda (PDF) (Report). Show Low, Arizona: Arizona State Transportation Board. July 20, 2018. pp. 310 to 339. Retrieved June 16, 2019.
  10. ^ Arizona Department of Transportation. "ADOT Right-of-Way Resolution 1973-P-074". Arizona Department of Transportation. Retrieved October 18, 2018.
  11. ^ Google (November 2, 2014). "Business Loop I-8 Gila Bend" (Map). Google Maps. Google. Retrieved November 2, 2014.