Originally, its northern terminus with the A 98 was merely a ninety-degree turn accompanied by a designation change.

At the southern end of the A 861 is the Rheinfelden border crossing with Switzerland.

A small portion of motorway connects this crossing to Switzerland's A 3 at junction 14.

This is to allow German traffic and Swiss traffic that do not have vignettes to cross between the Swiss and German halves of Rheinfelden without having to buy one.

A vignette is required to go past the junction Rheinfelden-West, as traffic then must enter the A 3.