The extent of forest, savanna, barrens, and prairie vegetation of Crawford County, Illinois, was mapped using the General Land Office survey notes of 1804-1821. Forest vegetation was the most extensive, covering 40.8% of the county, followed by prairie (34.2%), savanna (18.2%) and barrens (6.8%). Quercus alba L. (white oak) was the dominant forest species with an importance value (IV) of 60.6, followed by Q. velutina Lam. (black oak), Carya spp. (hickories), Ulmus spp. (elms), and Acer saccharinum L. (silver maple). In the savanna white oak again dominated (IV of 66.2), followed by black oak and hickories. The areas designated as barrens by the surveyors were dominated by white oak (IV of 78.8) followed by hickories, black oak, Acer saccharum Marsh. (sugar maple), and Fagus grandifolia Ehrh. (beech). Density (trees/ha) was 149.7, 18.2 and 29.7 for the forest, savanna and barren areas, respectively. Corylus americana Walt. (hazelnut) had the highest frequency for understory shrubs and was commonly associated with the forest prairie interface and barrens.