On March 25, 2011 archaeologist Michael R. Waters, director of the Center for the Study of the First Americans at Texas A&M University, and colleagues reported that excavations at the Buttermilk Creek Complex at the Debra L. Friedkin Paleo-Indian archaeological site in present day Salado, Texas, about 40 miles northwest of Austin, showed that hunter-gatherers were living at the Buttermilk Creek site and making projectile points, blades, choppers and other tools from local chert for a long time, possibly as early as 15,500 years ago (13,500 BCE) More than 50 well-formed artifacts as well as hundreds of flakes and fragments of chipping debris were embedded in thick clay sediments immediately beneath typical Clovis material. These discoveries predated the arrival of the Clovis people which were thought to have arrived from Asia circa 13,000 years ago (11,000 BCE).
Waters, Michael R. et al, "The Buttermilk Creek Complex and the Origins of Clovis at the Debra L. Friedkin Site, Texas," Science 331, no. 6024 (March 25, 2011) 1599-1603.
"Compelling archaeological evidence of an occupation older than Clovis (~12.8 to 13.1 thousand years ago) in North America is present at only a few sites, and the stone tool assemblages from these sites are small and varied. The Debra L. Friedkin site, Texas, contains an assemblage of 15,528 artifacts that define the Buttermilk Creek Complex, which stratigraphically underlies a Clovis assemblage and dates between ~13.2 and 15.5 thousand years ago. The Buttermilk Creek Complex confirms the emerging view that people occupied the Americas before Clovis and provides a large artifact assemblage to explore Clovis origins" (Abstract).