Interstate
Interstate 15, or I-15, is an interstate highway in the western United States. Its odd (as opposed to even) number indicates that it is primarily a north-south highway. It goes from San Diego, California just south of Interstate 8 (where it becomes California State Route 15) to Sweetgrass, Montana at the Canadian border. North of its junction with California State Route 91 in the Inland Empire near Corona, the route follows (roughly) the old US Route 91.
It is planned by CalTrans that this highway will be extended south to Interstate 5 along CA 15 to San Diego's Barrio Logan district once necessary upgrades to CA 15 are completed. Note there are three bypasses and loops identified as Interstate 215: in the Inland Empire region of California; in Las Vegas, Nevada; and in Salt Lake City, Utah.
In California, the designation of I-15 applies to five different named freeways. From I-8 (the Mission Valley Freeway) to the Riverside/San Diego county line, it is part of the Escondido Freeway. (The portion of the Escondido Freeway passing through the Marine Corps Air Station at Miramar is also known as the Semper Fi Freeway.) Betweem the county line and California State Route 78 (the Ortega Highway) in Lake Elsinore, it is known as the Temecula Valley Freeway. From CA-78 to Limonite Avenue in northwestern Riverside County, it is known as the Corona Freeway. From Limonite Avenue to the northern junction with the I-215 spur, it is named the Ontario Freeway. From the northern I-215 junction to the Nevada state line, I-15 is called the Mojave Freeway. Detailed information about freeway intersections and communities along these routes can be found at their individual entries.
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Length
| Miles | km | state | |
| 292 | 473 | California | |
| 124 | 201 | Nevada | |
| 29.40 | 47.63 | Arizona | |
| 401 | 650 | Utah | |
| 196 | 318 | Idaho | |
| 396 | 642 | Montana | |
| 1,438.40 | 2,330.21 | Total | |
Major Cities Along the Route
- San Diego, California
- Los Angeles, California's eastern Inland Empire suburbs
- Las Vegas, Nevada
- North Las Vegas, Nevada
- Salt Lake City, Utah
- Pocatello, Idaho
- Great Falls, Montana
Intersections with other Interstates
- Interstate 8 in San Diego, California
- Interstate 10 in Ontario, California
- Interstate 40 in Barstow, California
- Interstate 70 in Cove Fort, Utah
- Interstate 80 in Salt Lake City, Utah
- The western Interstate 84 in Ogden, Utah. They stay merged until Tremonton, Utah.
- The western Interstate 86 in Pocatello, Idaho
- Interstate 90 in Butte, Montana. They are merged for 9 miles.
Spur Routes
- Inland Empire, California - I-215
- Spur to Henderson, Nevada outside Las Vegas - I-515
- Beltway Las Vegas, Nevada - I-215
- Salt Lake City, Utah - I-215
- Butte, Montana - I-115
- Great Falls, Montana - I-315
Notes
Managed Lanes Project- Initated during fall 2003 and will finished late 2007. Portion of CA-56 to Centre City Pkwy (former US 395). More info in "reference" section; See also high occupancy toll.
At the time it was built, the section running through the northwest corner of Arizona (the Virgin River gorge) was the most expensive section (per mile) of the entire interstate system.
The sign for the Zzyzx exit, the alphabetically last place name in the United States, is a well-known landmark along the drive from Los Angeles to Las Vegas on I-15.
Interstate 15 had an eastern branch bypassing San Bernardino, California, and a western branch in Idaho. I-215 around San Bernardino was I-15E, and the western half of I-86 was once called I-15W.
I-215 around Salt Lake City was once known as I-415.
I-15 ends at the border between Montana and Alberta, where it becomes AB Provincial Highway 4. This route can be used to go into the cities of Calgary and Edmonton.
Reference
- http://www.ihoz.com/interstates.html
- http://www.dot.ca.gov/dist11/facts/I-15managed.pdf
- 2005 Rand McNally "The Road Atlas 2005" - newest feature- interstate mileage by state
| Primary Interstate Highways | 
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