Laurentia is a bioregion atop the Laurentian craton in the northeastern United States and eastern Canada, and centering on the Great Lakes. The bioregion spans the Eastern Woodlands of North America from the easternmost part of the Great Plains to the Atlantic Coast of the Northeastern United States and Canadian Maritimes. From north to south, it spans from the edge of the boreal forest in Canada, generally up to approximately the 50th parallel give or take a couple degrees of latitude and south to approximately the Ohio River, Potomac River and Ozarks.