Maps of diluvial boundaries for the North American midcontinent are presented by state and by sedimentary basin. The upper diluvial boundary is the base of Ice Age sediments. For most of the study area, the basal diluvial boundary is the erosional unconformity between Precambrian crystalline rock and the Phanerozoic sedimentary record. The exceptions are Proterozoic to Cambrian rifts: the Midcontinent, East Continent, Fort Wayne, Reelfoot, Rough Creek Graben, and Rome Trough rifts. These are remnants of severe crustal disruption at the onset of the Flood, with varying ratios of volcanic and sedimentary fill. This paper focuses on the basal marine diluvial boundary and the upper diluvial boundary, excluding the rifts, showing the volume and distribution of sediments of the Ice Age. Deep Proterozoic rifts will be addressed in Part II. Detailed state maps of the basal diluvial boundary are shown in the appendix. Maps of the study area reveal cratonic basins of varying size, show a thickening of diluvial strata toward the south, and show the extent of Ice Age deposition. All these aid in understanding the work of the Flood in this region.