Business Loop I-25 - Glenrock

U.S. 20-26-87 split with Interstate 25 and remain on their original route west through the town of Glenrock and Casper. Business Loop I-25 to Glenrock begins at Exit 160 near the Dave Johnston Power Plant. The business route departs the freeway alongside U.S. 20-26-87 to become Birch Street three miles to the west at the town line.

Within Downtown Glenrock, Business Loop I-25 separates from the US highways. While U.S. 20-26-87 proceed west toward Casper, Business Loop I-25 cosigns with WY 95 in a southwesterly direction along Fourth Street to rejoin Interstate 25 at Exit 165.