Projections of Paleoindian range mobility in the late Pleistocene are typically inferred from straight-line distances between toolstone sources and sites where artifacts of these raw materials have been found. Often, however, these sourcing assessments are not based on geologic analysis, raising the issue of correct source ascription. If sites of similar age can be linked to a toolstone source through geologic study, and direct procurement of toolstone can be inferred, geographic information systems (GIS) modeling of travel routes between the source and those sites can reveal route segments of annual rounds and aspects of landscape use. In the Hudson Valley of eastern New York, Paleoindian peoples exploited Normanskill chert outcrops for toolstone during the late Pleistocene. Here, we combine X-ray fluorescence sourcing results that link Normanskill chert artifacts at Paleoindian sites to the West Athens Hill source outcrop in the Hudson Valley with GIS least cost path analysis to model seasonal pathways of late Pleistocene peoples in northeastern North America.