The Brünig-Napf-Reuss line forms a geographical boundary in traditional Swiss culture (). Running from the Brünig Pass along the Napf region to the Reuss (which joins the Aare at Brugg), it partly separates western (Bernese German) and eastern (Zurich German) varieties of High Alemannic, although some places east of the line belong to the western dialect group (Schwyz, Zug). The line runs across the cantons of Lucerne and Aargau.