An inventory and monitoring program for species of non-volant small mammals was undertaken in Voyageurs National Park on the Minnesota-Canadian border. Other observations of mammals were made in and around the Park (1967–2004). Here we report species range extensions, most noted since 1982, for four species of rodents present in and/or around the Park and Superior National Forest. They are the white-footed mouse (Peromyscus leucopus), rock vole (Microtus chrotorrhinus), Franklin's ground squirrel (Spermophilus franklinii) and eastern gray squirrel (Sciurus carolinensis). We also report the expansions within the state of the badger (Taxidea taxus) and the raccoon (Procyon lotor), previously known to occur further north in Canada. The results are discussed in the context of inventorying strategies, anthropogenic global climate change and the reservoirs for diseases transmissible to humans.