The US government will close a nearly nine-mile (14km) stretch of road from 1 July along its border that runs between Montana and Alberta, citing security concerns.
The closure of the stretch, commonly referred to as Border Road, will end more than eight decades of informal crossings between farming communities on each side of the border.
The Trump administration cites a rise in irregular migration and drug smuggling for the decision.
Although the road lies on the Montana side of the US-Canada border, it is maintained by Alberta's Warner County which has already set aside funds to build a replacement.
Calling the move "unfortunate", Warner County's Chief Administrative Officer Shawn Hathaway told the BBC that Canadian officials were first informed last summer of the US plan to close the road.
