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?

full_context: Document 1: Barlow Pass (Oregon): 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.
Document 2: Cascade Range: The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades. The small part of the range in British Columbia is referred to as the Canadian Cascades or, locally, as the Cascade Mountains. The latter term is also sometimes used by Washington residents to refer to the Washington section of the Cascades in addition to North Cascades, the more usual U.S. term, as in North Cascades National Park. The highest peak in the range is Mount Rainier in Washington at 14411 ft .
Document 3: Meek Cutoff: The Meek Cutoff was a covered wagon road that branched off the Oregon Trail in northeastern Oregon. The road is named for frontiersman Stephen Meek, who was hired to lead the first wagon train along it in 1845. The journey was a particularly hard one, and many of the pioneers lost their lives.
Document 4: The Oregon Trail (series): The Oregon Trail is a series of educational computer games that began with the very first edition originally developed by Don Rawitsch, Bill Heinemann, and Paul Dillenberger in 1971 and produced by the Minnesota Educational Computing Consortium (MECC) in 1974. The original game was designed to teach school children about the realities of 19th-century pioneer life on the Oregon Trail. The player assumes the role of a wagon leader guiding a party of settlers from Independence, Missouri, to Oregon's Willamette Valley via a covered wagon in 1848.
Document 5: Mullan Road: Mullan Road was the first wagon road to cross the Rocky Mountains to the Inland of the Pacific Northwest. It was built by U.S. Army troops under the command of Lt. John Mullan, between the spring of 1859 and summer 1860. It led from Fort Benton, which at the time was in the Dakota Territory, then Idaho Territory from July 1863, and Montana Territory beginning in May 1864, and the navigational head of the Missouri River (and once farthest inland port in the world). The road connected to Fort Walla Walla, Washington Territory, near the Columbia River. The road previewed the route approximately followed of modern-day Interstate 15 and Interstate 90 through present-day Montana, Idaho, and Washington.
Document 6: Overland Trail: The Overland Trail (also known as the Overland Stage Line) was a stagecoach and wagon trail in the American West during the 19th century. While portions of the route had been used by explorers and trappers since the 1820s, the Overland Trail was most heavily used in the 1860s as an alternative route to the Oregon, California, and Mormon trails through central Wyoming. The Overland Trail was famously used by the Overland Stage Company owned by Ben Holladay to run mail and passengers to Salt Lake City, Utah, via stagecoaches in the early 1860s. Starting from Atchison, Kansas, the trail descended into Colorado before looping back up to southern Wyoming and rejoining the Oregon Trail at Fort Bridger. The stage line operated until 1869 when the completion of the First Transcontinental Railroad eliminated the need for mail service via Thais' stagecoach. Mostly used during the gold rush of 1848.
Document 7: Bannock Pass: Bannock Pass is a high mountain pass in the Beaverhead Mountains, part of the Bitterroot Range in the Rocky Mountains. The pass lies on the Montana-Idaho border on the Continental Divide, at an elevation of 7684 ft (2342 m) above sea level.
Document 8: Fort Ridgely and South Pass Wagon Road: The Fort Ridgely and South Pass Wagon Road (also known as Nobles Trail) was a wagon trail that was intended to connect Fort Ridgely in Minnesota Territory (now Minnesota) with South Pass in the Rocky Mountains of Nebraska Territory (now Wyoming). It was designed to link St. Paul with California via the Oregon Trail, however only a portion of the route was completed. The trail was promoted and supervised by William H. Nobles. Appropriations for the trail were authorized by the U.S. Congress on July 22, 1856. It was the first road built in Dakota Territory.
Document 9: The Oregon Trail (video game): The Oregon Trail is a computer game originally developed by Don Rawitsch, Bill Heinemann, and Paul Dillenberger in 1971 and produced by the Minnesota Educational Computing Consortium (MECC) in 1974. The original game was designed to teach school children about the realities of 19th-century pioneer life on the Oregon Trail. The player assumes the role of a wagon leader guiding a party of settlers from Independence, Missouri, to Oregon's Willamette Valley via a covered wagon in 1848.
Document 10: Lemhi Pass: Lemhi Pass is a high mountain pass in the Beaverhead Mountains, part of the Bitterroot Range in the Rocky Mountains and within Salmon-Challis National Forest. The pass lies on the Montana-Idaho border on the continental divide, at an elevation of 7373 feet above sea level. It is accessed via Lemhi Pass Road in Montana, and the Lewis and Clark Highway in Idaho, both dirt roads. Warm Springs Road, which roughly follows the divide in Montana, passes just west of the pass's high point.
Document 11: Oregon Trail: 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.
Document 12: Monida Pass: Monida Pass is a high mountain pass in the Rocky Mountains of the northwestern United States, at an elevation of 6820 ft (2079 m) above sea level on the Union Pacific Railroad and 6870 ft (2094 m) on adjacent Interstate 15.
Document 13: Parting of the Waters: Parting of the Waters is an unusual hydrologic site at Two Ocean Pass on the Great Divide, within the Teton Wilderness area of Wyoming's Bridger-Teton National Forest. Two Ocean Pass separates the headwaters of Pacific Creek, which flows west to the Pacific Ocean, and Atlantic Creek, which flows east to the Atlantic Ocean. At Parting of the Waters, at , North Two Ocean Creek flows down from its drainage on the side of Two Ocean Plateau and divides its waters more-or-less equally between its two distributaries, Pacific Creek and Atlantic Creek. From this split, Two Ocean Creek waters flow either 3488 mi to the Atlantic Ocean via Atlantic Creek and the Yellowstone, Missouri and Mississippi Rivers, or 1353 mi to the Pacific Ocean via Pacific Creek and the Snake and Columbia Rivers. In the marshy area of Two Ocean Pass adjacent to Parting of the Waters, water actually covers the Continental Divide such that a fish could swim from the Pacific Ocean to the Atlantic Ocean drainages. In fact, it is thought that this was the pass that provided the route for Yellowstone cutthroat trout to migrate from the Snake River (Pacific) to Yellowstone River (Atlantic) drainages.
Document 14: Blue Mountain Pass: Blue Mountain Pass is a high mountain pass in Oregon, United States that is traversed by U.S. Highway 95. It gets its name from Blue Mountain (elevation 7435), which is just west of the pass. Blue Mountain and Blue Mountain Pass are located in south eastern Oregon, approximately 25 miles north of the Nevada border. They are not a part of the similarly named Blue Mountains of north eastern Oregon.
Document 15: Register Cliff: Register Cliff is a sandstone cliff and featured key navigational landmark prominently listed in the 19th century guidebooks about the Oregon Trail, and a place where many emigrants chiseled the names of their families on the soft stones of the cliff it was one of the key checkpoint landmarks for parties heading west along the Platte River valley west of Fort John, Wyoming which allowed travelers to verify they were on the correct path up to South Pass and not moving into impassable mountain terrainsgeographically, it is on the eastern ascent of the Continental divide leading upward out of the great plains in the east of the U.S. state of Wyoming. It is notable as a historic landmark for 'registering' hundreds of emigrants on the Oregon Trail (thus also the other northern Emigrant Trails that split off farther west such as the California Trail and Mormon Trail) who came to follow custom and inscribed their names on its rocks during the western migrations of the 19th century. An estimated 500,000 emigrants used these trails from 1843–1869, with up to one-tenth dying along the way, usually due to disease.
ground_truth: 2170 mi