Two recent United States (U.S.) Supreme Court decisions severely curtailed federal protection for isolated wetlands (i.e., those completely surrounded by uplands). However, the true extent of the wetlands affected and hence the implications of the decisions are unknown. Best professional judgment from almost a decade ago estimated ≤20 % of contiguous U.S. wetland area to be isolated. We used the National Wetlands Inventory and an National Hydrography Dataset buffering process to mask where potential isolated wetlands (PIW) in an eight-state region of the southeastern and mid-Atlantic U.S. intersected stream, river, and lake buffers and identified 813,163 putative isolated wetlands covering 1,185,022.6 ha, or approximately 4.4 % (range: 0.9–7.1 %) of all wetland habitat across the study area. PIWs averaged 9.0 % of the total freshwater habitat area in each state (range 3.6–11.0 %), were densely occurring (average areal extent range: 0.34–3.66 ha/km2, study area average 1.53 ± 7.63 ha/km2 standard deviation (SD); average numerical extent range: 0.46–2.17 per km2, study area average 1.05 ± 1.99 per km2 SD), and typically small (median size 0.38 ha; average size 1.46 ± 6.81 ha SD). Approximately 50 % of the extant PIWs were expected to be in “reference” or good condition, as determined by examining the land use surrounding each wetland and applying a landscape-level measure of anthropogenic disturbance, the Landscape Development Intensity (LDI) index. The PIWs in this study area comprise nearly 3 % of the remaining 44.5 million ha of wetlands in the contiguous United States.