For decades, many archaeologists have maintained that humans spread across North and South America only at the end of the last ice age. They pointed to the oldest known tools, including spear tips, scrapers and needles, dating back about 13,000 years.
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While simultaneously cover up, hiding, discrediting finds that date to 130,000 years in California and sites that go back to 280,000 years in South America ; and then running out of the profession and ruining the archeologist who unearthed them.
I am a firm believer in multi timeline waves and multi path migration. There was an expansion from the South also. Not talked about much, and covered up, is that the most common place to find Clovis points is around the San Pedro River Valley in Az. I am sure they came up through Central America to the North before they came from the north to the South.