Interstate 8 (I-8) is an Interstate Highway in the southwestern United States. It runs from the southern edge of Mission Bay at Sunset Cliffs Blvd. in San Diego, California, almost at the Pacific Ocean, to the junction with Interstate 10, just southeast of Casa Grande, Arizona.^[2] In California, especially from eastern San Diego County to points east, Interstate 8 runs very close to the United States-Mexico border. At points in eastern Imperial County, the border is no more than half a mile (1 km) south of the Interstate.

I-8 at the Mountain Springs/In Ko Pah grade is routed down two separate canyons, as the freeway descends 4,000 vertical feet in 11 miles. This is the widest median on the entire Interstate Highway System. In places, the median is over 1.5 miles (2.4 km) wide. I-8 also has the lowest elevation of any interstate at 52 feet (16 m) below sea level near El Centro, California.

Route description

California

Much of I-8 in the Imperial Valley in California runs below sea level; in fact, at the New River near Seeley, CA, I-8 reaches the lowest land elevation in the entire Interstate system at -52 ft. (-16 m).

Arizona

East of Yuma, the eastbound and westbound lanes invert; that is, the carriageways run on the left side of the median for roughly three miles. Throughout the entire length of Interstate 8, it only intersects one U.S. highway (US 95 in Yuma).

History

I-8 was part of the original 1957 plan of Interstates, following US-80 from San Diego to Gila Bend, Arizona, then AZ-84 from there to Casa Grande.

Major intersections

• Interstate 5 in San Diego, California
• Interstate 805 in San Diego, California
• Interstate 15 in San Diego, California
• Interstate 10 in Casa Grande, Arizona

References