| State: | ND |
| Type: | US |
| Route: | 85B |
| Map: | U.S. Route 85B.svg |
| Length Mi: | 8.97 |
| Established: | 2015 |
| Direction A: | North |
| Terminus B: | in Williston |
| Junction: |
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| Direction B: | South |
| Terminus A: | in Williston |
| Counties: | Williams |
| Spur Of: | 85 |
| Spur Type: | US |
U.S. Route 85B (US 85B) is an approximately 9miles temporary auxiliary route of US 85 located entirely within Williams County in the state of North Dakota. The highway serves as an eastern bypass around the city of Williston.[1] The establishment of the route was a temporary solution to the rapid increase in truck traffic in the area due to the North Dakota oil boom. The county plans on eventually replacing the highway with an expressway bypass, dubbed the "Northeastern Truck Reliever Route", once funding is gathered.[2] US 85 already bypasses the city as an expressway to the west.
Starting from the north, US 85B follows 57th Street Northwest, traveling east from an intersection (located on the Williston city limits) with US 2 and US 85[3] —running concurrently with County Road 6 (CR 6)—before turning south after approximately 2miles, leaving the concurrency with CR 6. After turning south, the route continues in this direction for exactly 3miles,[4] before reaching an intersection with 54th Street Northwest that marks the eastern terminus of CR 7B. The route then continues south for about 3miles before curving west and maintaining a straight path for about NaNmiles, and then curving back to the south. After this, the route continues south for just under NaNmiles before terminating at a T intersection with North Dakota Highway 1804 (ND 1804) within Williston city limits. The highway runs roughly parallel to the Little Muddy River for most of its length.