Question: How long is this historic east–west, large-wheeled wagon route and emigrant trail in the United States on whch Barlow Pass is on?
Context: Barlow Pass is a 4155 ft mountain pass in the Cascades in Oregon, on the Oregon Trail, and a major milestone of the Barlow Road.  It is the crest of the Cascade Mountains: the dividing line between watersheds of the Deschutes River and those that flow into the Sandy River. Emigrant Pass is a mountain pass in Eureka County, Nevada, United States.  It originally carried the California Trail over the Emigrant Hills of northern Eureka County, reaching a peak elevation of 6125 ft .  Interstate 80 now follows the California Trail's route over the pass. The 1820s Malden Inn (also sometimes as "The Kreppsville Inn") and John Krepps Tavern is a historic building in the unincorporated bedroom community of Malden, Pennsylvania at the junction of South Malden Road and Old U.S. Route 40 (US40), the historic Cumberland Pike.  The Inn's Malden location (present-day borough of Centerville, PA) along the western part of the Amerindian trail known as Nemacolin's Path transformed into a wagon road linking the river ford between Brownsville–West Brownsville with the former frontier towns of Washington, Pennsylvania and Wheeling, West Virginia, where the Emigrant Trail then allowed an easy crossing the Ohio River.  The Inn had a good commercial site astride the old National Pike (U.S. Route 40 before the 1960s highway construction project) about three miles west of the long climb up from West Brownsville and Denbo Heights, PA being located at the former junction of Malden Road connecting northwards to Coal Center and California situated about half-the-way to Centerville from the Brownsville ford and the ferry terminus below Blainsburg just North-northeast of West Brownsville. The Oregon Trail is a 2170 mi historic east–west, large-wheeled wagon route and emigrant trail in the United States that connected the Missouri River to valleys in Oregon.  The eastern part of the Oregon Trail spanned part of the future state of Kansas, and nearly all of what are now the states of Nebraska and Wyoming.  The western half of the trail spanned most of the future states of Idaho and Oregon. Southern Emigrant Trail, also known as the Gila Trail, the Kearny Trail, Southern Trail and the Butterfield Stage Trail, was a major land route for immigration into California from the eastern United States that followed the Santa Fe Trail to New Mexico during the California Gold Rush.  Unlike the more northern routes, pioneer wagons could travel year round, mountain passes not being blocked by snows, however it had the disadvantage of summer heat and lack of water in the desert regions through which it passed in New Mexico Territory and the Colorado Desert of California.  Subsequently, it was a route of travel and commerce between the eastern United States and California.  Many herds of cattle and sheep were driven along this route and it was followed by the San Antonio-San Diego Mail Line in 1857-1858 and then the Butterfield Overland Mail from 1858 - 1861. The Nobles Emigrant Trail, also known as the Fort Kearney, South Pass and Honey Lake Wagon Road, is a trail in California that was used by emigrant parties from the east as a shortened route to northern California.  It was pioneered in 1851 by William Nobles, who discovered an easy shortcut between the Applegate Trail in Nevada and the Lassen Trail in California.  The trail was extensively used until the 1870s, when it was superseded by railroads. Granite Pass on the California Trail, located in what is now Cassia County, Idaho less than half a mile north of Utah, has historic significance dating to 1842 when it was found by Joseph B. Chiles to serve as an adequate emigrant trail route to come west toward California from the Oregon Trail route that went through Fort Hall.  Chiles was then returning east to Fort Hall in a small group that dropped out of the Bartleson–Bidwell Party, the first group attempting to emigrate with wagons from Missouri to California.  The Granite Pass can be seen from far away, coming from that direction.  When Chiles brought a west-bound wagon group through the pass in 1843 it became established.  The California Trail eventually evolved and went through this pass; Chiles led seven different groups through the pass.  When first used for emigrants as a wagon trail, it was part of Mexico. The Tucson Cutoff was a significant change in the route of the Southern Emigrant Trail.  It became generally known after a party of Forty-Niners led by Colonel John Coffee Hays followed a route suggested to him by a Mexican Army officer as a shorter route than Cooke's Wagon Road which passed farther south to cross the mountains to the San Pedro River at Guadalupe Pass. Robidoux Pass, also known as Roubadeau Pass, Roubedeau Pass, Roubideau Pass, Roubidoux Pass and Roubadeau Pass Gap, is a gap passing through the Wildcat Hills near Scottsbluff, Nebraska about 9 mi west of Gering, Nebraska.  The gap was on the route of the historic Oregon or Emigrant Trail.  It is at an elevation of 4554 ft .  Used by thousands of emigrants to the west from 1843-1851, the pass is a National Historic Landmark. West Brownsville is a former important transportation nexus and a present-day borough in Washington County, Pennsylvania, United States and part of the Pittsburgh metropolitan area.  The population was 1,075 at the 2000 census.  Culturally, by postal route, and socially, the community is part of cross-river sister-city Brownsville, for the two were long joined by the Amerindian trail known as Nemacolin's Path that became a wagon road after the American Revolution.  Brownsville was the first point where the descent from the Appalachians could safely reach the river down the generally steep banks of the Monongahela River.  Between Brownsville and West Brownsville was a shallow stretch, usable as a river ford astride a major Emigrant Trail to the various attractive regions in the Northwest Territory, the first National Road, the Cumberland Pike (Now U.S. Route 40 ).
Answer: 2170 mi