Reas Pass, elevation , is a mountain pass on the

Continental Divide A continental divide is a drainage divide on a continent such that the drainage basin on one side of the divide feeds into one ocean or sea, and the basin on the other side either feeds into a different ocean or sea, or else is endorheic, not ...

Fremont County, Idaho Fremont County is a county located in the U.S. state of Idaho. As of the 2020 census the county had a population of 13,388. The county seat and largest city is St. Anthony. The county was established in 1893, and was named for the explorer J ...

, about southwest of

West Yellowstone, Montana West Yellowstone is a town in Gallatin County, Montana, United States, adjacent to Yellowstone National Park. The population was 1,272 at the 2020 census. West Yellowstone is served by Yellowstone Airport. It is part of the Bozeman, MT Microp ...

. The pass lies essentially on the Idaho-Montana border, but modern maps show that the summit lies entirely in Idaho, because the Divide and the state line do not quite coincide here. The pass is also somewhat unusual in that, despite being the lowest crossing of the Divide in the vicinity, it has evidently never been traversed by a highway of any significance. Starting in 1909, it was used by a branch line of the

Union Pacific Railroad The Union Pacific Railroad is a Railroad classes, Class I freight-hauling railroad that operates 8,300 locomotives over routes in 23 U.S. states west of Chicago and New Orleans. Union Pacific is the second largest railroad in the United Stat ...

running between

Ashton, Idaho Ashton is a city in Fremont County, Idaho, United States. The population was 1,127 at the 2010 United States Census, 2010 census, and it is part of the Rexburg micropolitan area, Rexburg Micropolitan Statistical Area. The district is noted for s ...

and West Yellowstone; however, the line eventually became unprofitable and was closed in 1979.

References

Landforms of Fremont County, Idaho Rail mountain passes of the United States Mountain passes of Idaho {{FremontCountyID-geo-stub