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U.S. Route 12 or US 12 is an east-west United States highway, running from Grays Harbormarker on the Pacific Ocean, in the state of Washingtonmarker, to downtown Detroitmarker, for almost 2500 miles (4000 km). As a thoroughfare, it has mostly been supplanted by I-90 and I-94, but remains an important road for local travel.

The highway begins in Aberdeenmarker, Washingtonmarker at an intersection with US 101. Its eastern terminus is currently in downtown Detroitmarker, at the corner of Michigan and Cass Avenue.

Route description

Major cities


The western terminus of US 12 is located in Aberdeenmarker, Washingtonmarker. In the 1960s, a portion of US 12 was moved north to the town of Mortonmarker, when the Mossyrock Dammarker was built and flooded the towns of Kosmos and Riffe, along the Cowlitz River in Lewis Countymarker. A large portion of old, two-lane US 12 was replaced by Interstate 82 and Interstate 182 in the 1980s, between Yakimamarker and the Tri-Cities, though the freeways are still cosigned with the US 12 designation. The old two-lane highway now bears the name Wine Country Road. The highway loosely follows the eastbound leg of the Lewis and Clark Expedition, between Wallula, Washingtonmarker and Clarkston, Washingtonmarker, thus being marked as part of the Lewis and Clark National Historic Trailmarker. The east end of the highway in the state is at Clarkstonmarker, where the highway crosses the Snake River into Idahomarker at Lewistonmarker.

The Washington section of US 12, other than a concurrency with Interstate 5, is defined at Washington Revised Code § 47.17.055.


US 12 enters the state at Lewistonmarker, crossing the Snake River from Clarkstonmarker, Washingtonmarker. It ascends the Clearwater River, concurrent with US 95 for 7 miles (11 km). It reduces to a two-lane undivided highway and goes on to Orofinomarker, continuing up the middle fork of that river to Lowell, the junction of the Lochsa and Selway Rivers. It continues up the Lochsa and climbs to Lolo Passmarker at the Montanamarker border. This portion of the highway is also designated as part of the Lewis and Clark National Historic Trailmarker. Most of the highway in Idaho is within the Clearwater National Forestmarker. The eastern section of US 12, through remote mountain forest and up to Lolo Pass, was built in the early 1960s, making US 12 the last US highway constructed. No services are available between Lowell and Powell, about 70 miles (112 km) further east.


US 12 enters Montana Lolo Passmarker, 7 miles (11 km) southwest of Lolo Hot Springsmarker in the Lolo National Forestmarker. After passing Lolo Peakmarker to the south and traveling east for 33 miles (53 km), it meets with US 93 at Lolomarker and continues as a concurrency northeast for 11 miles (18 km), until it meets with Interstate 90 in Missoulamarker. It then overlaps I-90 for 69 miles (111 km), until Garrisonmarker, where it heads east through Avon and Ellistonmarker. Here US 12 passes through the Helena National Forestmarker and then on to the capital, Helenamarker, where it junctions with Interstate 15 and US 287. It then overlaps US 287 and heads southeast, toward Townsendmarker, where it splits off and heads east until it meets with US 89. It overlaps US 89 for 11 miles (18 km), until just past White Sulphur Springsmarker, where it continues east on its own for 233 miles (375 km), until the junction with Interstate 94 at Forsythmarker. The major junctions along the way are US 191 at Harlowtonmarker and US 87 at Roundupmarker. At exit 93 near Forsythmarker, US 12 overlaps I-94 for 48 miles (77 km), until Miles Citymarker, where it again splits off on its own and heads east for 89 miles (143 km) to southwestern North Dakotamarker, passing through Bakermarker on the way.

North Dakota

US 12 is a two-lane undivided highway that runs 87.47 miles (140.8 km), through Adamsmarker, Bowmanmarker and Slopemarker counties in southwest North Dakota. The speed limit is 65 mph (105 km/h) on rural segments, with slower posted speeds within the cities of Marmarthmarker, Rhamemarker, Bowmanmarker, Scrantonmarker and Hettingermarker. US 12 meets with US 85 in Bowman, the routes are concurrent for a short distance through the city.

South Dakota

US 12 enters South Dakota from North Dakota, as a rural two lane highway about 10 miles (16 km) west/northwest of Lemmonmarker. For approximately the next 70 miles (113 km), US 12 runs parallel to the border of North Dakota, sometimes within less than a mile. At Walkermarker, US 12 heads southeast for 37 miles (60 km), where it crosses the Missouri Rivermarker at Mobridgemarker. From there it continues east for 18 miles (29 km), until it meets with US 83 near Selbymarker. It overlaps US 83 for 7 miles (11 km) and for about half of that distance, it is an expressway. After leaving US 83, it turns due east and spends about 80 miles (129 km) as a rural two lane highway again. A few miles before reaching Aberdeenmarker, it becomes an at-grade expressway. After the junction with U.S. Route 281, it goes back to being two lane for a few miles, before once again becoming a 4 lane expressway, until 2 miles (3 km) before Waubaymarker. It then meets with Interstate 29 near Summitmarker. From there it is heads southeast 22 miles (35 km), until Milbankmarker. At Milbank, it turns back northeast for 10 miles (16 km), until it crosses into Minnesotamarker at Big Stone Citymarker, just south of Big Stone Lakemarker.

Legal Definition

The South Dakota section of US 12 is defined at South Dakota Codified Laws § 31-4-132.


From the South Dakota/Minnesota state line at Ortonvillemarker, to Wayzatamarker, US 12 is mostly a rural two-lane highway with a speed limit, with slower speed limits through towns and a four-lane surface arterial segment through the city of Willmarmarker. From western Wayzata to Interstate 394 in Minnetonkamarker, US 12 is a six-lane freeway. East of I-494marker, US 12 is invisibly concurrent with Interstates 394 and 94 through Minneapolismarker and St. Paulmarker to the Minnesota/Wisconsin state line at Hudsonmarker.

The Minnesota section of US 12 is defined as Routes 149, 26, and 10 in Minnesota Statutes §§ 161.115(80) and 161.114(2).


From Elkhorn, Wisconsinmarker to near the Illinois/Wisconsin state line, U.S. 12 is a freeway with a 65 mph (105 km/h) speed limit. It continues as a two-lane highway until it approaches the city of Whitewater, where a new bypass has been constructed. It is currently two lane, but can be expanded to four lanes. U.S. 12 continues west to Madisonmarker. As US 12 nears Madisonmarker, it merges with US 14, US 151 and US 18, to form the West Beltline Highway, a four to six-lane freeway that encircles the south and west portions of the city, with a speed limit of 55 mph (90 km/h).

From Middletonmarker, the highway continues, on a 15 mile (24 km) four-lane road completed in 2004, to cross the Wisconsin River at Sauk Citymarker.


In Illinois, US 12 is an arterial surface road that runs from Richmondmarker, southeast to Des Plainesmarker. It then turns due south through the Chicago metropolitan areamarker, joining with U.S. Route 45. In Stone Parkmarker, U.S. Route 20 joins U.S. 12/45. In Hickory Hillsmarker, U.S. 45 continues south, while U.S. 12/20 runs due east in the southwest suburbs. From Hickory Hills, U.S. 12/20 runs east nearly to the Lake Michiganmarker lakefront and then joins with U.S. Route 41, as all three routes travel southeast into the state of Indiana.

US 12 is referred to as Rand Road in Chicago's northwest suburbs. Rand is an original name for the area around Des Plaines, Illinoismarker, the location where the road resumes its westerly direction. South of Des Plaines, U.S. 12 follows Mannheim Road and then 95th Street, before merging with U.S. 41 on Ewing and Indianapolis Avenues toward the Indiana state line.


In Indiana, US 12 is a historically significant route, that winds along the southern coast of Lake Michiganmarker. It runs from an interchange with the Indiana Toll Road, concurrent with US Routes 20 and 41 in Whitingmarker, to Michiana Shoresmarker, at the Michiganmarker state line. A large portion of this segment is known as the Dunes Highway.


US 12 is now the only U.S. highway route still serving downtown Detroitmarker, whose street grid was laid by Augustus B. Woodward, to have a five-way intersection of the roads that would become US 12, US 10, US 16, US 112 and US 25. US 24 still travels through Detroit from Puritan to 8 Mile Road on the far-west-side.

As from the earliest days of its existence, US 12 enters Michigan from Indiana, southwest of New Buffalomarker and continues to the old junction of US 12 and US 112 in New Buffalo. It is now assigned between New Buffalo and Detroit (except through Ypsilanti), along what was US 112 until 1962.


Since the highway's creation in 1926, the eastern terminus has always remained within a few blocks of this point.

The western terminus was gradually extended westward, until it met up with the Pacific Oceanmarker.

Former ferry crossing

In 1925, U.S. 12 in Michigan was originally proposed to run from Detroitmarker to Ludingtonmarker, across Lake Michiganmarker, via the Pere Marquette Railway car ferry to Manitowoc, Wisconsinmarker and then continuing into Wisconsin, on what later became US-10, in those two states. Also, U.S. 12 originally went into Wyoming, before being rerouted into Montana and was proposed to go into Oregon, but did not.

Chicago freeway

U.S. 12 was originally planned to be a freeway from Chicagomarker to Madison, Wisconsinmarker. The portion from Genoa City, WI, to Elkhorn, WI was already being built when the Interstate system was announced. After the Interstate program was announced and due to the fact that Wisconsin was not able to obtain some right-of-way land north of Elkhorn, construction was stopped. Since construction was stopped, Illinois never built any of it, but the rough grading and off-ramps are still there in Illinois. In Elkhorn, the ramps also continue past the intersection where the construction stopped, but they are not used. Much of U.S. 12 in Illinois is a divided highway and it is surface road.

See also

Related US Routes

Notes and references

External links

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