Ohio Hopewell is an archaeological concept that is known worldwide but that suffers from “a disarray of radiocarbon results” (Lynott 2015:60). Here, we establish a comprehensive dataset of 425 14C dates from Ohio Hopewell sites and apply formal chronometric hygiene criteria to all dates. We then iteratively assess the temporal placement and span of the six most important Ohio Hopewell sites—the Hopewell Mound Group, Liberty, Mound City, Seip, Tremper, and Turner. A staged relaxation of hygiene criteria for our best three categories (Classes 1–3) permits alternate but generally consistent conclusions. As the first large-scale analyses of Ohio Hopewell temporality since the publication of IntCal20 (Reimer et al. 2020), the available data show a ritual complex that begins 90 or more years later than generally has been recognized circa 2010 14C BP, or as Bayesian modeled, AD 90–120. Our analysis reveals site histories of differing spans, more late dates than early dates, and with most Hopewell activity ending across these sites circa 1640 14C BP, or as Bayesian modeled, AD 395–430. An increased consideration of contingency in contemporary temporal reckoning increases the utility of the historical narratives that we as archaeologists can construct.