Interstate 15 (
I-15) is a major
Interstate Highway in the western
United States. I-15 begins near the
Mexican border in
San Diego County and stretches north to
Alberta, Canada, passing through the states of
California,
Nevada,
Arizona,
Utah,
Idaho, and
Montana. The interstate serves the cities of
San Diego,
Las Vegas,
St. George,
Salt Lake City,
Pocatello and
Butte. It also passes close to the urban areas of
Orange County, California,
Los Angeles County, California,
Ogden, Utah, and
Helena, Montana.