An early Native American site in the Reventazón river (Costa Rica) has been dated by radiocarbon to c. 12,000 years BP.
The date is consistent with others in North America (as old as c. 17,000 BP) and South America (c. 13,000 BP) marking the likely first inhabitation of the Western Hemisphere. It is anyhow the oldest prehistoric date known for Costa Rica.
The site which is being dug prior to the completion of a hydroelectric project, has been researched for several years now and has provided stone tools and weapons, as well as some charcoal (fire residues) that have allowed to date it.
Source: Pileta de Prehistoria[es].