For a very long time, archaeologists were certain the first settlers arrived in North America 10-12,000 years ago. Recent finds have made that untenable, pushing the date back to some 14,000 years BP (before present). New finds from Texas include stone tools from a soil layer 1.5m below that left by Clovis people 13,000 BP. The archaeologists reported the tools could be 13.5 to 15 thousand years old. They claim to have been very careful in watching for any indications sediments became mixed or overturned with time. If they are right, it pushes the migration further back, since the people who first came across the Bering Sea "land bridge" presumably needed hundreds or thousands of years to spread as far as Texas.
COMMENT: Remember the scene from the first X-Files movie allegedly set in Texas 37,000 years ago? Still fanciful, but not AS fanciful as we thought.