Davis et al. (Research Articles, 30 August 2019, p. 891) report human occupation at Cooper's Ferry, Idaho, USA, similar to 16,000 years ago, well before Greenland Interstadial 1 (GI-1). Critical review suggests that this early date is not supported by the evidence. Human occupation might have begun in the mid-16th millennium before the present, but would have been more likely after similar to 15,000 years ago, coeval with GI-1.