Although the smallmouth bass was originally found only in eastern North America, it has now been introduced over a much wider area. It has been successfully stocked in most U.S. states and has had extensive success on Canada's East Coast. Smallmouth stockings in Nova Scotia and New Brunswick have thrived, and there are good populations in B.C., Saskatchewan, and Manitoba. The native populations in southern Ontario and Quebec have expanded northwards to Timmins in Ontario and Hull in Quebec.

The native Canadian range of the largemouth bass covers the lower Great Lakes and the associated water systems of southern Ontario and Quebec. In the United States, the central to lower parts of the Mississippi River and lower southeastern states are the largemouth's original range. Now, because of aggressive stocking programs, it can be found throughout the eastern portion of the United States in great numbers, and in many of the southern states, right across to California. In fact, there are isolated pockets of largemouth in every continental U.S. state. The whole of southern Ontario and much of Quebec hold thriving populations of fish, and there are scattered pockets of bass in B.C., Alberta, Saskatchewan, and Manitoba.