The ice-free corridor through North America's interior is thought to have opened roughly 14,000 years ago, yet Cooper's Ferry contains evidence of human activity dating to 15,000–16,000 years ago.
Notes on verification
Confirmed by peer-reviewed Science paper (Davis et al. 2019), Oregon State University press release, and independent science journalism. Minor debate exists over exact dating reliability, but core claim is well-supported by primary and independent sources. [tier=gold indep_score=0.95 clusters=3 claim_tier=notable]
Sources
- 15,000-year-old Idaho archaeology site now among America's oldest (seed:history_and_archaeology)
- https://www.science.org/doi/10.1126/science.aax9830 (corroboration)
- https://www.science.org/content/article/first-people-americas-came-sea-ancient-tools-unearthed-idaho-river-suggest (corroboration)
- https://www.sci.news/archaeology/coopers-ferry-tools-07546.html (corroboration)
- https://news.oregonstate.edu/news/new-artifacts-suggest-first-people-arrived-north-america-earlier-previously-thought (corroboration)