The border returns to the Rhine downstream of the Rhine Falls, then separating the Waldshut district from the canton of Zürich, but then deviates from the river again to include the Rafzerfeld plain into Zürich's Bülach district (a right-bank territory historically acquired by the city of Zürich from the counts of Sulz in 1651). Downstream of Rafzerfeld, the border then sticks to the course of the Rhine until it enters the city of Basel, forming the northern border of the canton of Aargau as far as Kaiseraugst and then the canton of Basel-Land (municipalities of Pratteln and Muttenz) bordering on the German Lörrach district.