sentences:  A recent study in 2014 using Geographic Information System (GIS) Technologies, has redefined the extent of Proglacial Lake Tight.Using National Elevation Datasets (NEDs) from the USGS, the author incorporated the 275-meter (902-foot) contour elevations into a GIS, spatially correlated the contours with Ohio Department of Natural Resources' GIS glacial, geologic, and topographic datasets, and developed a revised lake boundary that shows the areal extent of Proglacial Lake Tight was approximately 40% larger than has been previously estimated, covering some 25,740 km2 (9,940 sq mi).This revised boundary shows that Lake Tight was as large as Lake Erie at its greatest extent.