 The highway also has extensive concurrencies with US 20 and US 26 along its east–west segment through the North Platte River valley.The Interstate has business loops through Cheyenne, Chugwater, Wheatland, Douglas, Glenrock, Casper, and Buffalo.I-25 enters Laramie County concurrent with US 87 from Weld County, Colorado, southwest of Cheyenne and briefly runs parallel to a BNSF Railway line.