Route 321 is a regional road in Quebec, Canada, that consists of two unconnected sections: one in Papineau Regional County Municipality that runs from Papineauville to Duhamel, and a second section of the road goes from Nominingue to L'Ascension in the Antoine-Labelle Regional County Municipality.The portion north of Chénéville in Papineau RCM is still unmarked on some maps, but it is signed on the road, and is very sinuous.