Wyoming Highway 89 follows State Control Route 10 for its entire length.
Southern segment
Wyoming Highway 89 has two different segments to its route. The first starts at I-80 / US 189 and Highway 150 in Evanston.. From Exit 5, WYO 89 heads north as Front Street into downtown Evanston. At, Highway 89 turns north onto Highway 89 north. From here, WYO 89 runs concurrent for a short distance with I-80 Business/US 189 Business until it intersects Bear River Drive where the business routes turn east. As Highway 89 leaves Evanston behind the roadway heads northwest. The highway passes through the former coal mining camp of Almy and reaches the Town of Bear River just before reaching the Utah state line. Bear River is one of Wyoming's newest towns, being incorporated in 2001. Just after leaving Bear River, WYO 89 temporarily ends at Utah State Route 16.
Utah connection
The roadway continues as Utah SR 16. SR 16 intersects SR-39 in Woodruff, Utah at from its start at WYO 89. SR-16 ends at SR-30 in Sage Creek Junction, Utah at. SR-30 'East' travels back to Wyoming State Line, where at, SR-30 ends and WYO 89 resumes.
Northern segment
The northern segment of Wyoming Highway 89 begins at Utah State Route 30 at the Utah-Wyoming state line west of Sage, Wyoming. WYO 89 travels northeast to US 30 at Sage. Here, WYO 89 turns north to join US 30 as it heads north WYO 89 runs concurrent with US 30 for almost from Sage through Cokeville, north to one-half mile east of the Idaho-Wyoming state line. This section is also known as the Emigrant Trail. At, US 30/WYO 89 intersects WYO 231 and WYO 232 in the Town of Cokeville. From there WYO 89 continues with US 30 north. At, WYO 89 ends its concurrency with US 30 near Border Junction. Wyoming Highway 89 heads north from U.S. Route 30 as it continues westward. WYO 89 then travels north for approximately, closely paralleling the Idaho-Wyoming state line until it finally crosses it and finally ends near Geneva, Idaho. The roadway continues as Idaho State Highway 61 for a very short length of, until US 89 in Geneva, Idaho.
History
According to an original network map of Wyoming State Highways, this route was defined as Wyoming Highway 65 in 1924. With the introduction of US routes in 1926, the route between Cokeville and Star Valley was renamed Highway 89, while the section south of Sage remained designated as Highway 65. This was done in the hopes that US 89 would be extended north into Wyoming. US 89 was extended in 1936 along old Highway 287. Highway 89 was recommissioned as Highway 91 to avoid confusion between the two highways, while Highway 65 kept its original number. However, within a few years, US 89 was rerouted to its current route in Utah and Idaho, and US 189 was created along old Highway 287. As a result, Wyoming recommissioned Highway 89 over both Highway 65 and Highway 91.