 U.S. Highway 12 | ||||
|---|---|---|---|---|
| Lewis and Clark Highway Northwest Passage Scenic Byway | ||||
 US 12 highlighted in red | ||||
| Route information | ||||
| Maintained byITD | ||||
| Length | 174.410 mi[1] (280.686 km) | |||
| Existed | 1962–present | |||
| Tourist routes |  Northwest Passage Scenic Byway | |||
| Major junctions | ||||
| West end |  US 12 atWashington state line inLewiston | |||
| Major intersections |  US 95 inLewiston | |||
| East end | US 12 atMontana state line atLolo Pass | |||
| Location | ||||
| Country | United States | |||
| State | Idaho | |||
| Counties | Nez Perce,Clearwater,Lewis,Idaho | |||
| Highway system | ||||
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U.S. Route 12 (US-12) is aUnited States Numbered Highway inNorth Central Idaho. It extends 174.410 miles (280.686 km) from theWashington state line inLewiston east to theMontana state line atLolo Pass,[1] generally along the route of theLewis and Clark Expedition, and is known as theNorthwest Passage Scenic Byway.[2] It was previously known as the Lewis and Clark Highway.
US-12 enters Idaho at the Washington state line in Lewiston,Nez Perce County, crossing theSnake River at the state line. It heads east through Lewiston, turning north to cross theClearwater River on theClearwater Memorial Bridge.[3] It then intersectsState Highway 128 (SH-128) and turns east to overlapUS-95 along a limited-access section with two lanes traveling each direction. The overlapped highways run east along the north bank of the Clearwater River for 7.3 miles (11.7 km), leaving Lewiston and entering theNez Perce Indian Reservation before separating.[1]
US-12 then continues east along the north bank of the Clearwater River through northernLapwai, past the Ant and Yellowjacket rock formation and a historical marker for theSpalding Mission.[4][5][6] It intersectsSH-3 near Arrow and crosses the Clearwater River again.[1][7][8][9][10][11]
US-12 then continues east along the south bank of the Clearwater River past historical markers commemorating Indian houses and the ghost town ofSlaterville, and, in a rest area atLenore, a historical marker for the Lenore Tram.[5]
EnteringClearwater County, US-12 continues east along the south bank of the Clearwater River throughOrofino. Just after leaving Orofino, it briefly overlapsSH-7, then continues southeast along the south bank of the Clearwater River, past a historical marker for the point where Lewis and Clark first found a western-flowing river.[1][5]
InLewis County, US-12 continues southeast along the south bank of the Clearwater River, intersectingSH-11 atGreer and passing a historical marker for a ferry operated in the original 1860 goldrush.[1][5] It then continues southeast intoKamiah, where it intersectsSH-162. It then crosses the Clearwater River again and leaves Kamiah.
It then entersIdaho County and continues south along the north bank of the Clearwater River, crossing theNez Perce National Historical Park. In the park, it passes a historical marker for two sites located about two miles (3.2 km) away, commemorating the Lewis and Clark Long Camp of 1806 and the Asa Smith mission of 1839 to 1841.[5][12] It then continues south along the north bank of the Clearwater River, intersectingSH-13 across the river fromKooskia. The highway then turns east along the north bank of the Clearwater River, passing a historical marker commemorating the camp ofNez Perce led byLooking Glass, and the1877 attack by theU.S. Army on July 1 that provoked Looking Glass to join the Nez Perce retreat withChief Joseph.[1][5] It continues east along the north bank of the Clearwater River, leaving the Nez Perce reservation. US-12 then continues toLowell, where it turns northeast along the north bank of theLochsa River through theBitterroot Mountains.
US-12 passes historical markers for Whitehouse Pond, Lewis and Clark's crossing of the Lolo Trail in 1806, and their crossing of theLolo Pass summit in 1805, before crossing Lolo Pass at 5,233 feet (1,595 m) to enterMontana.[1][5][13] From there it descends pastLolo Hot Springs toLolo, the junction withUS-93, near the site of Lewis and Clark'sTraveler's Rest.
US-12 was created in 1925 as part of the original system of U.S. Highways, and its original western terminus was inMiles City, Montana. In 1962, the highway was extended west to Lewiston, ending at the formerUS-410. In 1967, it was extended to its current western terminus inAberdeen, Washington, with the Idaho section taking its current route.[14]
The Lewis and Clark Highway, fromLewiston eastward toLolo Pass, was designatedSH-9 in 1916 and construction began in 1920.[15][16]Federal prison labor was used in the late 1930s to early 1940s,[17] andJapanese internment labor was used during the last two years ofWorld War II, working out of theKooskia Internment Camp, six miles (9.7 km) upstream ofLowell,[18][19][20][21] just below milepost 104.
By late 1955, 27 miles (43 km) remained unfinished,[16][22][23] and, upon its completion in 1962, it was redesignated US 12.[24][25][26] At the dedication ceremony at Lolo Pass attended by thousands on August 19, the states' governors,Robert E. Smylie of Idaho andTim Babcock of Montana, cut through a ceremonialwestern redcedar log at Packers Meadow with atwo-mancrosscut saw.[25][27][28]
The bridge crossing the Clearwater River near Arrow opened for traffic in early 1973.[7][8][9][10][11] The route previously was on the river's south bank between the bridge andSpalding, where it crossed on the old Spalding bridge; damaged by ice jams 10 years earlier,[29] it was dismantled shortly after the Arrow bridge opened.[11][30][31]
The currentSH-9 is entirely inLatah County and runs for less than 14 miles (23 km); it starts nearDeary atSH-8 and runs northwest, connecting withSH-6 near Harvard.
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US-12 through Idaho has been proposed as a route for shipment of huge equipment from Lewiston, an inlandport,[32] to oil sands facilities nearFort McMurray,Alberta and to a refinery inBillings, Montana. On two-lane portions of the road, the equipment, weighing as much as 300 short tons (270 t; 270 long tons) and as much as 30 feet (9.1 m) high and 24 feet (7.3 m) wide, would occupy the entire roadway. The route is preferable to other routes due to the lack of underpasses and the great distances involved. The alternative is transport across theGreat Plains fromTexas orNew Orleans.[33] On US-12, the major obstacles were powerlines, which had to be raised or buried. That and other alterations to the highway such as turnouts would be paid for by the companies. The trucks would transport only at night, moving short distances between places where they would pull off and let traffic pass. A permit granted by theIdaho Transportation Department toConocoPhillips in August 2010 is the subject of litigation initiated by householders along the route.[34] On January 19, 2011, it was announced that the Idaho government would issue permits for four loads of refinery equipment to be transported from Lewiston to Billings.[35]
The Port of Lewiston is the furthest inland seaport in theWestern U.S. It ships wheat, barley, and legumes to Asia and the South Pacific as well as the Middle East and Africa. There are also inland seaports inWashington at the port ofClarkston and Port of Wilma inWhitman County.
| County | Location | mi[1] | km | Destinations | Notes |
|---|---|---|---|---|---|
| Snake River | 0.000 | 0.000 |  US 12 west –Walla Walla | Continuation into Washington | |
| Interstate Highway Bridge | |||||
| Nez Perce | Lewiston | 2.605 | 4.192 |  SH-128 – Port Districts | |
| 2.831 | 4.556 |  US 95 north –Moscow,Coeur d'Alene | Western end of US 95 overlap | ||
| | 10.036 | 16.151 |  US 95 south –Grangeville,Boise | Eastern end of US 95 overlap | |
| | 14.950 | 24.060 |  SH-3 north –Juliaetta,Kendrick | ||
| Clearwater | | 43.980 | 70.779 |  SH-7 north (Michigan Avenue) –Orofino | Western end of SH-7 overlap |
| | 44.393 | 71.444 | SH-7 south (Gilbert Grade Road) | Eastern end of SH-7 overlap | |
| Lewis | Greer | 51.568 | 82.991 |   SH-11 east –Weippe,Pierce | |
| Kamiah | 66.220 | 106.571 |  SH-162 south –Nezperce | ||
| Idaho | | 73.850 | 118.850 |  SH-13 south –Kooskia | |
| Lolo Pass | 174.410 | 280.686 | US 12 east –Missoula | Continuation into Montana | |
1.000 mi = 1.609 km; 1.000 km = 0.621 mi
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 U.S. Route 12 | ||
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