Business Route 15 - Interstate Business Loop Guide
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Interstate Business Route 15

Interstate 15 has 30 active business routes, almost all of which replace old U.S. 91.

CALIFORNIA
Escondido Active The southernmost Business Loop 15 is Centre City Parkway, an expressway-grade route through Escondido. Business Loop I-15 is one routing of old U.S. 395 through North San Diego County -- the other old U.S. 395 went through the city on an older alignment. This business route is one of the best-signed business routes in California. In 1999, there was a southern "end" Business Loop I-15 sign, but by 2001, that sign was removed. However, the business loop still receives top billing on one of the advance signs from California State Route 78, which is unusual for California business loops. According to the California State Highway System Signing Log (October, 1991), Business Loop I-15 in Escondido runs from "Interstate 15 and South Direct Connection undercrossing near Escondido south city limits over Centre City Parkway to Interstate 15 and Escondido Expressway near Escondido north city limits."

On December 31, 2000, Chris Sampang wrote, "There is a minor section of actual grade-seperated freeway on old U.S. 395 (Business Loop I-15, Centre City Parkway) in Escondido; this is the interchange between the California 78 freeway and the Centre City Parkway. From California 78 looking north, the Centre City Parkway looks like an average four-lane rural [expressway], and traffic volumes didn't seem high - but this was December 30th."

Lake Elsinore Active The Lake Elsinore loop follows Main Street (old California 71), but it is very poorly signed once you leave the freeway. This route is locally maintained. According to the California State Highway System Signing Log (October, 1991), Business Loop I-15 in Lake Elsinore runs from Interstate 15 and Main Street over Main Street to Graham Avenue. Loop 15 "north" runs from Main Street over Graham Avenue to Riverside Avenue (California 74), and Loop 15 "south" runs from Main Street over Lakeshore Drive and Railroad Canyon to Interstate 15.
Norco Active Relatively new business route along Hammer Avenue (old California 31) in Norco. According to the signage, this business route does not extend south into Corona or north to California State Route 60. This route is locally maintained. Norco is short for "North Corona." This loop is not in the 1991 state signing log.
Victorville Active The Victorville business route is locally maintained with the exception of its concurrent section with State Route 18. Business Loop I-15 follows Seventh Street and D Street (State Route 18), and it is part of Historic U.S. 66-91. According to the California State Highway System Signing Log (October, 1991), Business Loop I-15 in Victorville runs "from Interstate 15 and Palmdale Road overcrossing over Seventh Street and State Route 18 (D Street) to Interstate 15 and Legislative State Route 18 separation."
Barstow Active Business Loop I-15 serves Barstow via Main Street and Historic U.S. 66 and old U.S. 91. According to the California State Highway System Signing Log (October, 1991), Business Loop I-15 in Barstow follows Main Street.
Baker Active Check out the Mojave thermometer and Bun Boy, the only attractions on this instance of Business Loop I-15. No signage, either from the freeway or along the main street, exists for Business Loop I-15, calling this loop into question. Locally maintained, this is old U.S. 91-466. The Baker loop is not listed in the 1991 state signing log.

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NEVADA
Las Vegas Decommisioned A few maps, including a Compass map of Las Vegas, refer to Nevada 604 (Las Vegas Blvd. / The Strip) and possibly Nevada 601 (Main Street) as Business Loop I-15 in the 1980s and even 1990s. I have never seen signs for Business Loop I-15 in Las Vegas, let alone Nevada 604 or Nevada 601 signs!
Mesquite Active The only existing Business Loop I-15 in Nevada serves Mesquite via Mesquite Boulevard, which is cosigned with Nevada 144 and is old U.S. 91. Click here for photos.
UTAH
St. George Active Business Loop I-15 through St. George shares pavement and sign assemblies with U-18 (St. George Blvd.) and U-34 between Exits 6 and 8. According to Dan Stober, Utah practice is to designate the old route as a state route and assign a state route number to it, leaving UDOT in charge of maintenance of the business route. Motorists following a business route will see green business loop shields as they head toward the center of a town on a business loop, and then will see the standard red, white, and blue shields with a "TO" placard as they leave a city center headed toward the freeway. This is also how Wyoming also signs its business routes.

Additionally, Utah places Utah beehive route shield containing the state route number at either end of the route. Wyoming and Utah both consider their business routes to be part of the state highway system. Some other states, such as Ohio, Minnesota, and California generally do not include business routes within their respective state highway systems. This generally leads to less signage standards for business routes both from the freeway and within cities and towns. For an example of Utah's state route shield signing, see the picture in the I-15 Nephi business loop entry.
Cedar City Active Business Loop I-15 through Cedar City is also U-130 and old U.S. 91 between Exits 57 and 62.
Parowan - Paragonah Active Business Loop I-15 follows hidden U-274 and Old U.S. 91 between Exits 71 and 82.
Beaver Active Business Loop I-15 is hidden U-160 via Old U.S. 91 between Exits 109 and 120.
Fillmore Active Business Loop I-15 follows hidden U-99 via Old U.S. 91 between Exits 163 and 167.

Holden Active Business Loop I-15 follows U-64 and U.S. 50 via Old U.S. 91 between Exits 174 and 178.
Nephi Active U-41 (U-28 ends at the south I-15 Nephi interchange, and U-41 continues north into town as the Business Loop 15 between Exits 222 and 229. This is also old U.S. 91.
Layton Active Dan Stober writes, "I checked on that mysterious BL 15 that is signed from northbound Interstate 15 at exit 332 in Layton. Unfortunately, once you take the exit, there is not one trailblazer to guide you along the loop -- not at the bottom of the exit ramp, and nowhere along U-126 (where the BL would be if it existed). I don't know how you want to handle these on your page. From my perspective, if the business route isn't signed from the parent, as in Brigham City, then it does not serve its purpose. And, if there is no signage to help you follow the business loop, as in Layton, then it's worthless."
Brigham City Active Dan Stober writes, "I was on a road trip on 11/21/98, and I stumbled across a marked Business Loop I-15/84 in Brigham City. There are consistent trailblazers all along the route; the problem is that it is not signed from the freeway in either direction (which is why I told you it doesn't exist). Basically, the route follows U-13 through town."
Tremonton Active Co-signed with Business Loop I-84. This is another rare dual Interstate business loop, as this serves both Interstates 15 and 84. (Brigham City's loop also serves the same two Interstates.) The routes split at the western edge of town, just as the parent Interstates do. U-102 continues on as a standalone route both east and west of the business loop. The eastern leg of the loop is part of U-13, giving the U-13 the distinction of hosting business loops in two different cities!
IDAHO
Malad City ? Found this one on a DeLorme's Idaho Atlas; this is old U.S. 191, not 91. Dan Stober says it doesn't exist upon field inspection, so we'll leave this one with a "?" status.
Downey - Virginia Active Old U.S. 191
McCammon Active Business Loop I-15 serves McCammon via U.S. 91 between Exits 44 and 47.
Inkom Active Business Loop I-15 serves Inkom via old U.S. 91 and 191 between Exits 57 and 58.
Pocatello Active Business Loop I-15 serves Pocatello via Fifth Avenue and Yellowstone Avenue (rejoining Interstate 15 at the Pocatello Creek Road Interchange). This route is partially cosigned with U.S. 30 and U.S. 91 between Exits 67 and 71.
Blackfoot Active Business Loop I-15 serves Blackfoot via U.S. 91 (old U.S. 191) between Exits 89 and 93. During the late 1980s and early 1990s, Rand McNally incorrectly showed Business Loop I-15 following what's left of U.S. 91 between Blackfoot and Idaho Falls between Exits 89 and 118; in reality, these two towns are served by two different I-15 business routes.
Idaho Falls Active Business Loop I-15 serves Idaho Falls via Yellowstone Avenue (U.S. 26) and Broadway (Business U.S. 20). It is worthy to note that U.S. 91 officially ends on Business Loop I-15 and U.S. 26 south of Idaho Falls, so that highway does not enter the city. However, the Yellowstone Avenue section of Business Loop I-15 follows old U.S. 91, prior to its drastic reduction.
Hamer/Dubois ?  
MONTANA
Dillon Active Business Loop I-15 follows old U.S. 91 between Exits 62 and 63.
Butte Active Business Loops I-15 and I-90 serves Butte between Interstate 15-90 Exit 124 and 127. This route includes all of signed Interstate 115 and Harrison Avenue. Business Loop I-15 follows old U.S. 10-91, and it is cosigned with Business Loop I-90 throughout.
Helena Active Business Loop I-15 serves Helena via Prospect Avenue, Eleventh Avenue, Last Chance Gulch, Main Street, and Cedar Street between Exits 192 and 193. U.S. 12 and Business Loop I-15 separate, with U.S. 12 taking an alternate route across the city via Euclid Avenue, Lyndale Avenue, and Montana Avenue.
Great Falls Active From the south, Business Loop I-15 serves Great Falls via eastbound Tenth Avenue South (U.S. 89 and Montana State Route 200), the north-south one-way couplet of Fifth and Sixth Avenues, and westbound Central Avenue between Exits 278 and 280. The business route does not intersect with U.S. 87, as U.S. 87 enters the city from the east via Tenth Avenue South, turns north along the north-south one-way couplet of 14th and 15th Streets, and exits the city to the northeast. The southern, freeway-grade end of Business Loop I-15 has the privilege, for 0.82 of a mile, to be Interstate status; more specifically, it is Interstate 315. Interstate 315 is signed as Business Loop I-15, not as an Interstate highway, but it has been in the Interstate Route Log and Finders List since the 1960s. The highway was completed in 1967, and a decision was reached by state highway engineers not to refer to it as Interstate 315 since it is such a short route. For more information, see the Interstate 315 listing. Interstate 315 leaves Interstate 15 at Exit 278 and ends at Fox Farm Road, with one exit at 14th Street SW.
Conrad Active Business Loop I-15 serves Conrad via old U.S. 91 between Exits 335 and 339.
Shelby Active Between Loop I-15 serves Shelby via old U.S. 91 between Exits 363 and 364.

Page Updated March 21, 2006.