Interstate 5

at Tejon Pass to around ft to m|1600 at Grapevine near the southernmost point of the San Joaquin Valley, approximately mi to km|30|abbr=yes south of Bakersfield and mi to km|4|abbr=yes south from where State Route 99 splits away from it in Wheeler Ridge.

From Highway 99 to south of Tracy, I-5 skirts along the far more remote western edge of the great Central Valley, and thus here is removed from population centers such as Bakersfield and Fresno with other state highways providing connections. Interstate 580 splits off from I-5 at a point south of Tracy, providing a loop-route connection to the San Francisco Bay Area. After passing Tracy, I-5 heads north through Stockton and Sacramento before turning west to Woodland. At Woodland, the interstate heads northwest again towards Dunnigan, where it converges with Interstate 505.

From Dunnigan, I-5 skirts north along the western edge of the Sacramento Valley to Red Bluff. I-5 then enters the Shasta Cascade region, passing through Redding and Shasta Lake before climbing up to near the foot of Mount Shasta. The interstate then travels to Weed and Yreka before reaching the Oregon border.

Oregon

About mi to km|3|abbr=yes north of the California border, the highway crosses ft to m|4310 Siskiyou Summit, the highest point on I-5. Dropping down into Rogue River valley through Oregon's southern mountains and towns such as Ashland, Medford and Grants Pass. Turning north across three passes to the Umpqua Valley and through Roseburg, the mountains tend to turn into hills, and as it reaches Cottage Grove, the road enters the Willamette River Valley. At Eugene the highway intersects with the short Interstate 105. The interstate then heads almost due north, skirting Albany and Corvallis, and passes through Salem. There were plans to build a spur into Salem, Oregon, called Interstate 305. I-5 covers convert|308|mi|km in Oregon.

Just north of Salem, between mile marks 259 and 260, placed in the median is a sign where the 45th parallel crosses I-5. It bears the words "45 Parallel half way between the Equator and the North Pole".

The highway then tracks a little to the northeast, Interstate 205 splits off south of the Portland metro area. From here it passes up through Tualatin and Tigard along former U.S. Route 99W before hitting the southern terminus of I-405 and the Marquam Bridge. Also planned was a spur in Portland off I-405, called Interstate 505, but it was never built and has been removed from city plans. A stub of I-505 exists as a long exit ramp to U.S. Route 30.

After crossing the Willamette River on the Marquam Bridge, I-5 has junctions at the western terminus of Interstate 84 and the northern terminus of I-405. It then continues through the northern parts of the city of Portland, and crosses into Washington via the Interstate Bridge.

Washington

The highway begins in Washington over the Columbia River and drops down into the city of Vancouver. About seven miles (11 km) into the state, it reaches the northern terminus of I-205, which is on the eastern edge of the Portland-Vancouver metropolitan area. It then tracks north by northwest to Kelso and Longview, at which point it ceases paralleling a large bend of the Columbia. Continuing north through the Willapa Hills, the freeway eventually reaches Olympia, where it bends sharply east, after that it goes through Fort Lewis and by McChord AFB, then finally Tacoma where it bends sharply north again to reach Seattle. The Ship Canal Bridge carries it over Portage Bay in Seattle. The freeway makes its way out of the Seattle/Tacoma/Everett metro area, crosses the floodplains of three rivers, through the Skagit Valley and the Mount Vernon-Anacortes Metropolitan Area to the northern city of Bellingham to arrive at the Peace Arch Canadian border crossing between Blaine, Washington, and Surrey, British Columbia. Highway 99 continues northwesterly from the border into Vancouver, B.C. I-5 covers convert|277|mi|km in Washington.

History

An extensive section of this highway (over convert|600|mi|km), from approximately Stockton, California, to Portland, Oregon, follows very closely the track of the Siskiyou Trail. [http://www.museumsiskiyoutrail.org Museum of the Siskiyou Trail] ] The Siskiyou Trail was based on an ancient network of Native American footpaths connecting the Pacific Northwest with California's Central Valley. By the 1820s, trappers from the Hudson's Bay Company were the first non-Native Americans to use the route of today's I-5 to move between today's Washington State and California. During the second half of the 19th century, mule trains, stagecoaches, and the Central Pacific railroad also followed the route of the Siskiyou Trail. By the early 20th century, pioneering automobile roads were built along the path of the Siskiyou Trail, notably the Pacific Highway. The Pacific Highway ran from British Columbia to San Diego, California, and was the immediate predecessor of much of U.S. Route 99. The route of U.S. 99 was in turn used as a basis for much of the route of today's I-5.

In 1988, smoke from nearby field burning caused a 23-car pileup near Albany, Oregon, leading to 7 deaths and 37 injuries. This accident resulted in more regulation of field burning. [ http://extension.oregonstate.edu/oap/story.php?S_No=72&storyType=oap&cmd=pf]

Major intersections

*Interstate 805 (bypass) in south San Diego, California
*"Interstate 15 in San Diego, California (future; this freeway is currently signed as State Route 15)"
*Interstate 8 in San Diego, California [Exit 20]
*Interstate 805 (bypass) in north San Diego, California [Exit 26B]
*Interstate 405 (bypass) at the El Toro Y in Irvine, California
*Interstate 605 in Santa Fe Springs, California [Exit 123]
*Interstate 710 southeast of downtown Los Angeles, California
*Interstate 10 at the East Los Angeles Interchange complex, east of downtown Los Angeles, California
*Interstate 405 (bypass) in Sylmar, California
*Interstate 210 in Sylmar, California
*Interstate 580 in Tracy, California
*Interstate 205 in Tracy, California
*Interstate 305 in Sacramento, California (hidden, known as Business Loop 80.)
*Interstate 80 in Sacramento, California
*Interstate 505 in Dunnigan, California
*Interstate 105 in Eugene, Oregon [Exits 194A and 194B]
*Interstate 205 (bypass) in Tualatin, Oregon (southern junction) [Exit 288]
*Interstate 405 (bypass) in Portland, Oregon (southern junction) [Exit 299B]
*Interstate 84 in Portland, Oregon [Exit 300B]
*Interstate 405 (bypass) in Portland, Oregon (northern junction) [Exit 302C]
*Interstate 205 (bypass) in Salmon Creek, Washington (northern junction) [Exit 7]
*Interstate 705 in Tacoma, Washington [Exit 133]
*Interstate 405 (bypass) in Tukwila, Washington (southern junction) [Exit 154A]
*Interstate 90 in Seattle, Washington [Exit 164B]
*Interstate 405 (bypass) in Lynnwood, Washington (northern junction) [Exit 182]

Auxiliary routes

*San Diego, California - I-805
*San Diego, California - I-905 (future)
*Los Angeles, California - I-105
*Los Angeles, California - I-605
*Los Angeles and Orange County, California - I-405
*Tracy, California - I-205
*Sacramento, California - I-305 (unsigned)
*Zamora, California - I-505
*Eugene, Oregon - I-105
*Portland, Oregon - I-405
*Portland, Oregon and Vancouver, Washington - I-205
*Tacoma, Washington - I-705
*Seattle, Washington - I-405

I-5 will have a complete set of auxiliary routes (105, 205, 305, 405, 505, 605, 705, 805, 905), with the completion of Interstate 905 in San Diego. Currently, Interstate 80 and Interstate 90 are the only two interstates to have complete sets of auxiliary routes, by the numbers.

References