Interstate 5

Interstate 5
Route information
Length:	1,381.29 mi[1] (2,222.97 km)
History:	Designated in 1956 Completed in 1979
Major junctions
South end:	Fed. 1 at the Mexican border at San Ysidro, CA
	SR 15 in San Diego, CA I‑8 in San Diego, CA US 101 in Los Angeles, CA I‑10 in Los Angeles, CA US 50 in Sacramento, CA I‑80 in Sacramento, CA I‑84 in Portland, OR I‑90 in Seattle, WA US 2 in Everett, WA
North end:	BC 99 at the Canada–US border at Blaine, WA
Location
States:	California, Oregon, Washington
Highway system
Interstate Highway System Main Auxiliary Suffixed Business

Interstate 5 (I-5) is the main Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the continental U.S. and U.S. Route 99 from Mexico to Canada, through the states of California, Oregon and Washington. It serves some of the largest cities on the U.S. West Coast, including Seattle, Portland, Sacramento, Los Angeles, and San Diego, and also links the capital cities of Washington (Olympia), Oregon (Salem), and California (Sacramento) together. The highway's southern terminus is the Mexican border and its northern terminus is the Canada–US border; it is currently the only continuous Interstate highway to touch the U.S. borders with both Canada and Mexico. Upon crossing the Mexican border at its southern terminus, Interstate 5 continues to Tijuana, Baja California as Mexico Federal Highway 1. Upon crossing the Canada–US border at its northern terminus, it continues to Vancouver as British Columbia Highway 99. It is the 12th longest highway in the U.S. following I-15 and the fifth longest north-south highway following I-15.

I-5 links to control cities in California (San Diego, Santa Ana, Los Angeles, San Francisco, Sacramento, Redding, Mount Shasta, Weed, and Yreka), Oregon (Ashland, Medford, Grants Pass, Roseburg, Eugene, Salem, and Portland), and Washington (Seattle, Tacoma, Olympia, and Vancouver). North of Seattle, the control city is Vancouver, British Columbia; it is signed as "Vancouver B.C." in order to avoid confusion with Vancouver, Washington.

One notable control city that I-5 does not directly reach is San Francisco, which is about 80 miles (130 km) west of the highway. To the south, in the Tracy area, I-580 splits from I-5 towards San Francisco, while to the north, near Vacaville, I-505 cuts south to I-80, which serves that city. That routing, via I-580, I-80, and I-505, was planned originally as I-5W.^[2][3]

Route description

Lengths

	mi[1]	km
CA	796.53	1281.89
OR	308.14	495.90
WA	276.62	445.18
Total	1381.29	2222.97

California

Interstate 5 in the Newhall Pass Interchange where I-5 intersects with Interstate 210 and State Route 14 near Santa Clarita

The southernmost point of I-5 is at the Mexican border at the San Ysidro border crossing, one of the busiest in the world.^[4] Beginning at the border in San Ysidro, which is part of the city of San Diego, as the John J. Montgomery Freeway, I-5 goes through the suburbs of Chula Vista and National City before reaching downtown San Diego. It then parallels the Pacific coastline, going through the northern suburbs of San Diego, bisecting the University of California, San Diego campus, and passing the I-805 merge (where it becomes the widest Interstate in the United States for a short stretch), before passing through the 28 miles (45 km) of Marine Corps Base Camp Pendleton in northern San Diego County. Here I-5 is also known as the San Diego Freeway.

At Dana Point, I-5 turns inland and heads due north through Mission Viejo to the El Toro Y interchange in southeastern Irvine. I-5 becomes the Santa Ana Freeway as it runs southeast to northwest, passing through major cities and suburbs in Orange and Southern Los Angeles counties. Southern Californians refer to it as "the 5 Freeway" or as the Santa Ana Freeway in the Los Angeles area. From this point, the San Diego Freeway continues northward as I-405.

When the freeway reaches the East Los Angeles Interchange one mile (1.6 km) east of downtown Los Angeles, I-5 becomes the Golden State Freeway. The route continues through the San Fernando Valley and then crosses the Newhall Pass through the Santa Susana Mountains into the Santa Clarita Valley. The interchange with State Route 14 (SR 14) is unusual in that truck traffic is separated into its own lanes for both the mainline of the freeway and the transition ramps to and from SR 14. For about a four-mile (6.4 km) stretch between Santa Clarita Valley and the Pyramid Lake, the northbound and southbound lanes separate and cross sides, with the southbound lanes running to the east of the northbound ones. At that point, the Golden State Freeway rises sharply to the north through the Grapevine to eventually reach the second-highest point of its entire length, the Tejon Pass (elevation 4,183 ft or 1,275 m). Through the Tehachapi Mountains. Path 26 power lines generally follow the freeway along this stretch. The freeway then descends sharply for 12 miles (19 km) at Tejon Pass to around 1,600 feet (490 m) at Grapevine near the southernmost point of the San Joaquin Valley, approximately 30 miles (48 km) south of Bakersfield and 4 mi (6.4 km) south from where SR 99 splits away from it in Wheeler Ridge.

I-5 south approaching Weed and Mt. Shasta.

From SR 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; other state highways provide these connections. I-580 splits 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 I-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

In downtown Portland, Interstate 5 runs adjacent to the Willamette River and passes by the Moda Center, and Oregon Convention Center.

About three miles (4.8 km) north of the California border, the highway crosses 4,310 feet (1,310 m) Siskiyou Summit, the highest point on I-5, and then drops down into the Rogue 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 I-105, a short spur route into Downtown Eugene. Some city highways intersect on I-5 in the Eugene Metro. The Interstate then heads almost due north, skirting Albany and Corvallis, passing through Salem, and crossing through Woodburn. There were plans to build a spur, called I-305, into Salem. I-5 covers 308 miles (496 km) in Oregon.

Just north of Salem, between mile markers 259 and 260 just short of mile marker 260, signs in the median and on both shoulders mark the place where the 45th parallel crosses I-5. It reads "45th Parallel half way between the Equator and the North Pole".

The highway then tracks a little to the northeast, and I-205 splits off south of the Portland metro area. From here I-5 passes through Tualatin and Tigard along former U.S. Route 99W (US 99W) before hitting the southern terminus of I-405 and the Marquam Bridge. Also planned was a spur in Portland off I-405, called I-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 US 30.

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

Interstate 5 passing through downtown Seattle.

Washington

The highway begins 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 through Woodland to Kelso and Longview, at which point it ceases to parallel a large bend of the Columbia River. Continuing north between the Willapa Hills and the Cascade foothills, the freeway eventually reaches Olympia, where it bends sharply east. The highway passes though the northern end of Joint Base Lewis-McChord (formerly Fort Lewis and McChord Air Force Base) and Tacoma, where it bends sharply north again to reach Seattle. The Ship Canal Bridge carries it over Portage Bay in Seattle. The freeway continues north out of the Seattle–Tacoma–Everett metro area, crosses the floodplains of three rivers, through the Skagit Valley and the Mount Vernon–Burlington Metropolitan Area to the northern city of Bellingham, to arrive at the Peace Arch Canada–US border crossing between Blaine, Washington, and Surrey, British Columbia. Highway 99 continues northwest from the border into Vancouver, BC. I-5 covers 277 miles (446 km) in Washington.

History

The shield for U.S. Route 99.

A section of the 1915 Ridge Route in Lebec, California, abandoned when US 99 (later upgraded to I-5) was constructed over the Tejon Pass in order to make the travel straighter and safer.

An extensive section of this highway (over 600 miles (970 km)), from approximately Stockton, California, to Portland, Oregon, follows very closely the track of the Siskiyou Trail.^[5] This 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.^[5] 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 US 99. The route of US 99 was in turn used as a basis for much of the route of today's I-5.

A major deviation from the old US 99 route is the Westside Freeway portion of I-5 in California's Central Valley. To provide a faster and more direct north-south route through the state, the decision was made to build a new freeway to the west and bypass Fresno, Bakersfield, and the rest of population centers in the area instead of upgrading the existing highway (which was re-designated as part of SR 99).^[6] This re-route through California's Central Valley was the last section of I-5 to be constructed, with the final segment dedicated and opened to traffic near Stockton, California, on October 12, 1979. Representatives from both Canada and Mexico attended the dedication to commemorate the first contiguous freeway connecting the North American countries.^[7]

This direct route also bypasses San Francisco and the rest of the San Francisco Bay Area. Original plans called for a loop Interstate with a directional suffix, I-5W.^[6] This route now roughly corresponds to I-580 from I-5 south of Tracy to Oakland, I-80 from Oakland to Vacaville, and I-505 from Vacaville to I-5 near Dunnigan. I-5W and most of the other Interstates around the country with directional suffixes were eventually renumbered or eliminated. Nevertheless, San Francisco is still listed as a control city on northbound I-5 between SR 99 and I-580.

On May 23, 2013, a portion of a bridge on I-5 collapsed in Washington (near Mount Vernon, between Seattle and the Canada–US border at mile marker 228.3), sending two cars into the water and requiring traffic in both directions to bypass the crossing.^[8] The Washington State Department of Transportation used a temporary structure to restore access across the river while a permanent bridge replacement was built. That process was completed September 15, 2013.^[9]

Junction list

Looking South at I-5 and I-90 meeting in Seattle.

Welcome to Oregon sign

California

Fed. 1 at the Mexican border in San Ysidro

I‑805 in San Ysidro

SR 905 on the Nestor–San Ysidro–Otay Mesa West neighborhood line (future I-905)

SR 15 on the Barrio Logan–Southcrest–Logan Heights neighborhood line (future I-15)

I‑8 in San Diego

I‑405 in Irvine

I‑605 on the Downey–Santa Fe Springs city line

I‑710 in Commerce

US 101 in Los Angeles

I‑10 in Boyle Heights. The highways travel concurrently through Boyle Heights.

I‑405 on the Mission Hills–Granada Hills neighborhood line

I‑210 in Sylmar

I‑580 southwest of Vernalis

I‑205 south-southwest of Lathrop

I‑305 / US 50 in Sacramento

I‑80 in Sacramento

I‑505 south-southeast of Dunnigan

US 97 in Weed

Oregon

US 199 east of Grants Pass

I‑105 on the Eugene–Springfield city line

US 20 in Albany

I‑205 in Tualatin

I‑405 in Portland

I‑84 / US 30 in Portland. I-5/US 30 travels concurrently through Portland.

I‑405 / US 30 in Portland

Washington

I‑205 on the Salmon Creek–Mount Vista CDP line

US 12 south-southeast of Napavine. The highways travel concurrently to Grand Mound.

US 101 in Tumwater

I‑705 in Tacoma

I‑405 in Tukwila

I‑90 in Seattle

I‑405 on the Lynnwood–Martha Lake–Alderwood Manor line

US 2 in Everett

BC 99 at the Canada–US border in Blaine

Auxiliary routes

• San Diego, California—I-805
• Los Angeles, California—I-105
• Los Angeles and Orange County, 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 (i.e. 105, 205, 305, 405, 505, 605, 705, 805, 905), with the completion of I-905 in San Diego County. Currently, I-80 and I-90 are the only two Interstates to have complete sets of auxiliary routes.

References

1. Staff (December 31, 2013). "Table 1: Main Routes of the Dwight D. Eisenhower National System Of Interstate and Defense Highways as of December 31, 2013". Route Log and Finder List. Federal Highway Administration. Retrieved March 17, 2014.
2. "Interstate 580 California". Interstate-Guide. Retrieved September 19, 2011.
3. "Interstate 505 California". Interstate-Guide. Retrieved September 19, 2011.
4. "Busiest border crossing". Interstate-guide.com. Retrieved November 27, 2011.
5. "Museum of the Siskiyou Trail". Museumsiskiyoutrail.org. Retrieved November 27, 2011.
6. "Routes 1-8". California Highways. Retrieved September 19, 2009.
7. Staff. "Timeline of Notable Events of the Interstate Highway System in California". California Department of Transportation. Retrieved March 2, 2014.
8. Valdes, Manuel (May 24, 2013). "'Horrified' trucker watches I-5 bridge collapse behind him". Seattle: KOMO-TV. Retrieved May 24, 2013. Officials warned it could be weeks before things returned to normal along the heavily travelled corridor.
9. Staff. "I-5–Skagit River Bridge Replacement". Washington State Department of Transportation. Retrieved November 29, 2013.

External links

Route map: Bing / Google

• Interstate 5 at the Interstate Guide