|Lewis and Clark Highway,|
Northwest Passage Scenic Byway
US highlighted in red
|Maintained by ITD|
|Length||174.410 mi  (280.686 km)|
|Northwest Passage Scenic Byway|
|West end||Washington state line in Lewiston|
|US 95 in Lewiston|
|East end||Montana state line at Lolo Pass|
|Counties||Nez Perce, Clearwater, Lewis, Idaho|
US Route 12 (US 12) is a federal highway in north central Idaho. It extends 174.210 miles (280.364 km) from the Washington state line in Lewiston east to the Montana state line at Lolo Pass, generally along the route of the Lewis and Clark expedition,  and is known as the Northwest Passage Scenic Byway  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 the Snake River at the state line. It heads east through Lewiston, turning north to cross the Clearwater River and intersect SH-128. It continues east to overlap US 95 along a limited access section. The overlapped highways run east along the north bank of the Clearwater for 7.3 miles (11.7 km), leaving Lewiston and entering the Nez Perce Indian Reservation before separating. 
US 12 then continues east along the north bank of the Clearwater through North Lapwai, past the Ant and Yellowjacket rock formation and a historical marker for the Spalding Mission.    It continues east to intersect SH-3 and cross the Clearwater again. 
US 12 then continues east along the south bank of the Clearwater past historical markers commemorating Indian houses and the ghost town of Slaterville, and, in a rest area at Lenore, a historical marker for the Lenore Tram.   
Entering Clearwater County, US 12 continues east along the south bank of the Clearwater through Orofino. Just after leaving Orofino, it briefly overlaps SH-7, then continues southeast along the south bank of the Clearwater, past a historical marker for the point where Lewis and Clark first found a western-flowing river.   
In Lewis County, US 12 continues southeast along the south bank of the Clearwater, intersecting SH-11 at Greer and passing a historical marker for a ferry operated in the original 1860 gold rush.    It then continues southeast into Kamiah, where it intersects SH-162. It then crosses the Clearwater again and leaves Kamiah.
It then enters Idaho County, and continues south along the north bank of the Clearwater, crossing Nez Perce National Historical Park. In the park, it passes a historical marker for two sites located about two miles (3 km) away, commemorating the Lewis and Clark Long Camp of 1806 and the Asa Smith mission of 1839 to 1841.   It then continues south along the north bank of the Clearwater, intersecting SH-13 across the river from Kooskia. The highway then turns east along the north bank of the Clearwater, passing a historical marker commemorating the camp of Nez Perce led by Looking Glass, and the July 1, 1877 attack by the U.S. Army that provoked Looking Glass to join the Nez Perce retreat with Chief Joseph.    It continues east along the north bank of the Clearwater, leaving the Nez Perce reservation. US 12 then continues to Lowell, where it turns northeast along the north bank of the Lochsa River through the Bitterroot Mountains.
US 12 passes historical markers for Whitehouse Pond, Lewis and Clark's crossing of the Lolo Trail in 1806, and their crossing of the Lolo Pass summit in 1805, before crossing Lolo Pass at 5,233 feet (1,595 m) to enter Montana.     
US 12 was created in 1925 as part of the original system of United States highways, and its original western terminus was in Miles City, Montana. In 1962, the highway was extended west to Lewiston, ending at the former US 410. In 1967, it was extended to its current western terminus in Aberdeen, Washington, with the Idaho section taking its current route. 
The Lewis and Clark Highway, from Lewiston eastward to Lolo Pass, was designated State Route 9 in 1916 and construction began in 1920.   Federal prison labor was used in the late 1930s and Japanese internment labor was used during the last two years of World War II, working out of the Kooskia Internment Camp, six miles (10 km) upstream of Lowell,     just below milepost 104. ( )
By the fall of 1955, 27 miles (43 km) remained unfinished,   and upon its completion in 1962, it was redesignated US 12.    At the dedication ceremony at Lolo Pass attended by thousands on August 19, the states' governors, Bob Smylie of Idaho and Tim Babcock of Montana, cut through a ceremonial cedar log at Packers Meadow with a two-man crosscut saw.   
U.S. Route 12 through Idaho has been proposed as a route for shipment of huge equipment from Lewiston, an inland port,  to oil sands facilities near Fort McMurray, Alberta and to a refinery in Billings, Montana. On two-lane portions of the road, the equipment, weighing as much as 300 tons and as much as 30 feet (9 m) high and 24 feet (7 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 the Great Plains from Texas or New Orleans.  On US 12, the major obstacles were power lines, 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 the Idaho Transportation Department to ConocoPhillips in August 2010 is the subject of litigation initiated by householders along the route.  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. 
The Port of Lewiston is the furthest inland seaport in the western United States. 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 in Washington at the port of Clarkston and Port of Wilma in Whitman County.
|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|
- Idaho Transportation Department. "Milepost Log, US 12" (PDF). Retrieved June 3, 2017.
- Idaho Byways - Northwest Passage Scenic Byway Archived 2013-06-25 at the Wayback Machine.
- "Leaders arrive for L-C Highway dedication". Lewiston Morning Tribune. Idaho. August 19, 1962. p. 1.
- Campbell, Thomas W.; Hamilton, Ladd (August 20, 1962). "Thousands witness L-C Highway dedication". Lewiston Morning Tribune. (Idaho). p. 1.
- "Dedication festivity opens Idaho-Montana road link". Spokesman-Review. (Spokane, Washington). August 20, 1962. p. 1.
- Wakeley, Daniel A. (August 20, 1962). "New route opens rugged land". Spokane Daily Chronicle. (Washington). p. 1.
- National Park Service (November 12, 1999). "Ant and Yellowjacket". Retrieved 2009-01-11.
- Idaho Transportation Department (May 26, 2005). "Idaho Highway Historical Marker Guide Index". Archived from the original on December 15, 2008. Retrieved 2009-01-11.
- National Park Service (November 20, 1999). "Spalding Site". Retrieved 2009-01-11.
- Groundspeak Inc. (2008). ""Slaterville" Waymark". Retrieved 2009-01-11.
- Groundspeak Inc. (2008). ""Lenore Tram" Waymark". Retrieved 2009-01-11.
- Groundspeak Inc. (2008). ""Lewis and Clark" Waymark". Retrieved 2009-01-11.
- Groundspeak Inc. (2008). ""Gold Rush Ferry" Waymark". Retrieved 2009-01-11.
- North Central Idaho Travel Association (2008). "Asa Smith Mission and Lewis and Clark Long Camp". Retrieved 2009-01-11.[ dead link]
- Groundspeak Inc. (2008). ""Looking Glass" Waymark". Retrieved 2009-01-11.
- Clearwater Web Services. "Lewis and Clark in Idaho, 1803-1806 Expedition: Highway 12". Archived from the original on September 23, 2008. Retrieved 2009-01-11.
- Groundspeak Inc. (2008). ""Lolo Trail Crossing" Waymark". Retrieved 2009-01-11.
- Groundspeak Inc. (2008). ""Lolo Summit" Waymark". Retrieved 2009-01-11.
- Federal Highway Administration (May 7, 2005). "U.S. 12: Michigan to Washington". Retrieved 2009-01-11.
- "Lewis & Clark Highway link-up is urged for national defense". Lewiston Morning Tribune. September 24, 1950. p. 1-sec 2.
- Forbes, Bob (November 29, 1953). "Hiking the Wash-ho-tana in Lochsa wilds". Spokesman-Review. Spokane, Washington. p. 9-This Week.
- Wegars, Priscilla. "Asian American Comparative Collection: The Kooskia Internment Camp Project". University of Idaho. Retrieved July 27, 2013.
- "Kooskia Internment Camp Scrapbook". University of Idaho. Retrieved July 27, 2013.
- Geranios, Nicholas K. (July 27, 2013). "Researchers uncover little-known internment camp". Yahoo! News. Associated Press. Retrieved July 27, 2013.
- Banse, Tom (August 5, 2010). "Archaeologists Resurrect Nearly Forgotten WWII Internment Camp". Oregon Public Broadcasting. Retrieved July 27, 2013.
- Johnson, Johnny (October 6, 1955). "L-C Highway has entrancing history". Lewiston Morning Tribune. Idaho. p. 1-LCSE.
- "Highway 12 label approved by Idaho highway board". Lewiston Morning Tribune. Idaho. Associated Press. June 26, 1962. p. 7.
- "Columbia-Snake Corridor: The West Coast Alternative" website Port of Lewiston, accessed October 22, 2010
- On the Great Plains, there are also inland ports on the Mississippi River and its tributaries as far north as Sioux City, Iowa, on the Missouri River.
- Tom Zeller, Jr. (October 21, 2010). "Oil Sands Effort Turns on a Fight Over a Road". The New York Times. Retrieved October 22, 2010.
- "Idaho: Giant Trucks Win Permit". The New York Times. Associated Press. January 19, 2011. Retrieved January 19, 2011.
|U.S. Route 12|