After the freeway bends back to the southeast, it intersects the eastern end of Wyoming Highway 345 (WYO 345), then crosses the BNSF Railway[3] (formerly the Chicago, Burlington and Quincy Railroad) and the Tongue River.

The highway intersects WYO 342 and Prairie Dog Creek Road at diamond interchanges before US 87 merges back into and becomes concurrent with I-90.

[3] The highway travels east, parallel to WYO 51 and then meets Adon Road, then curves to the southeast toward Moorcroft.

The highway passes over US 14 with no access and then meets its second exit in the city: the eastern terminus of its business loop.

[4] Jefferson Lines provides intercity bus service along the length of I-90 in Wyoming serving Gillette, Buffalo, and Sheridan along the route.

[5] During early planning of I-90, the town of Clearmont (on US 14) filed suit against the Wyoming Highway Commission for an alleged violation of a 1955 state law that required approval from voters for the construction of a bypass.

[6] Clearmont had previously been selected for a rerouting of US 14 and US 16 in 1957, which was seen as a precursor to a later Interstate Highway; the straighter route was also supported by business groups in Sheridan.

[8][9] Construction of I-90 in northwestern Wyoming began during the appeals process, with 58 miles (93 km) under active contracts for grading and site preparation by December 1960.

[9] The first section to open in Wyoming ran 6.9 miles (11.1 km) north of Sheridan and was completed in 1961.

[11] The longest stretch, 65 miles (105 km) between Buffalo and Gillette, was dedicated on October 14, 1962, and cost $18.4 million to construct.

[14] The final Wyoming section of I-90 was opened to traffic on October 10, 1985, following four years of construction on 10 miles (16 km) between the Montana state border and Ranchester.