Global Range: Highly disjunct eastern and western ranges. Arctic, Atlantic, and Mississippi River basins from Labrador and northern Quebec west to western Manitoba and south to the Roanoke River drainage, Virginia, and Tennessee River drainage, northern Alabama and northern Georgia; isolated populations in the extreme upper Santee (North Carolina), Savannah (South Carolina and Georgia), Coosa (Georgia), and Osage (Missouri) river systems. Western North America in the upper Missouri River basin, Alberta, Montana, and Wyoming; upper Columbia River drainage; upper Colorado River drainage, northern New Mexico, Colorado, and Wyoming; isolated populations in endorheic basins in Utah and Nevada (Page and Burr 1991, Andersen and Deacon 1996). After forthcoming taxonomic changes are published, Cottus "bairdi" (in the restricted sense) will be restricted to the Ohio River and tributaries, some Great Lakes tributaries, and upper Susquehanna River tributaries. Cottus bairdi also occurs in the upper reaches of Wills Creek (a Potomac River tributary) as a result of stream capture (Rich Raesly, pers. comm., 2002). Unique forms are found in the Columbia/Lower Snake, Upper Snake/Bonneville basins, Colorado River system, Malheur Basin (Oregon), Upper Missouri River system, western/northern Great Lakes tributaries, Ozarks, Tennessee/Cumberland systems, the Smokies (3+ taxa), and the upper Kanawha (New) River (Dave Neely, pers. comm., 2000).
Due to uncertainties in the distributional details of members of the Cottus bairdii complex, the watershed (HUC) map in NatureServe Explorer depicts the distrbution of the complex, including Cottus bairdii and species now recognized as Cottus bendirei and Cottus hubbsi. The ranges of individual species will be mapped separatey when further information becomes available.