Interstate 5

Interstate 5 is a major north–south Interstate Highway on the West Coast of the United States. It runs from the Mexico–United States border near San Diego to the Canada–United States border near Blaine, Washington, serving as the primary transportation corridor for the coastal states of California, Oregon, and Washington. The highway connects major metropolitan areas including Los Angeles, Sacramento, Portland, and Seattle, and is a critical route for interstate commerce and travel.

Route description

From its southern terminus at the San Ysidro Port of Entry, it traverses the length of California, closely following the paths of historic routes like U.S. Route 99 and the El Camino Real. It bisects the Los Angeles Basin, passes through the Tejon Pass in the Tehachapi Mountains, and runs through the Central Valley alongside the California Aqueduct. In Oregon, it follows the Willamette Valley, passing near Mount Shasta and Crater Lake before reaching the Columbia River at Portland. Crossing into Washington via the Interstate Bridge, it continues north through the Puget Sound region, passing Mount St. Helens and Mount Rainier before terminating at the Peace Arch border crossing in Blaine.

History

The route's planning was formalized with the Federal-Aid Highway Act of 1956, which created the Interstate Highway System. Much of its alignment was built upon or parallel to older highways like U.S. Route 99 and the Pacific Highway. Key construction projects included the replacement of the original Ridge Route in California with the "Grapevine" segment through the Tejon Pass, the completion of the San Diego Freeway through Los Angeles, and the construction of the Interstate Bridge over the Columbia River between Portland and Vancouver. The final segment was completed with the opening of the Ship Canal Bridge in Seattle in the early 1960s.

Major junctions

Major junctions from south to north include interchanges with Interstate 8 and Interstate 805 in San Diego; a complex confluence with Interstate 10, U.S. Route 101, and State Route 110 in Los Angeles; junctions with Interstate 580 and Interstate 80 near Sacramento; and a meeting with Interstate 84 in Portland. In Washington, it intersects with Interstate 90 in Seattle and Interstate 405 in Lynnwood before reaching its northern terminus. Other significant crossings include the Interstate 605 and the John Wayne Airport area via State Route 73.

Auxiliary routes

Several three-digit auxiliary Interstate Highways serve its corridor. In California, these include Interstate 105 (the Glenn Anderson Freeway), Interstate 205, Interstate 305 (unsigned), Interstate 405, Interstate 505, Interstate 605, and Interstate 805. The Oregon segment is supplemented by Interstate 105 in Eugene and Interstate 205 east of Portland. In Washington, key auxiliary routes are Interstate 205, Interstate 405, and Interstate 705 in Tacoma.

See also

* U.S. Route 101 * Alaska Highway * Pan-American Highway * California State Route 99 * Cascade Range * Oregon Department of Transportation * Washington State Department of Transportation

Category:Interstate 5 Category:Interstate Highway System Category:Transportation in California Category:Transportation in Oregon Category:Transportation in Washington (state)