The area was naked and barren at 13,000 year ago. At the 12,600 years ago layer, they found traces of bison, hare and sage brush. So the area was not open to human travel at 13,000 years ago. There was a physical corridor, but it would be 400 years before humans could have traveled that corridor. So people entering the Americas could not have done so unless they traveled along the Pacific Coast.
We know that people with stone tools had populated the Americas before 13,000 years ago. Before 12,600 years ago, there was no wood for fuel and tools, game animals for food, clothing and shelter in the so called ice free corridor. So the Clovis Culture that had established itself in the Americas by 13,000 years ago, had to have arrived by way of coastal travel by canoes.
There were earlier Pre-Clovis peoples who arrived by the same coastal route at Monte Verde in Chile and Paisley Cave in Oregon before the arrival of the Clovis Culture immigrants 1,500 years before the arrival of the Clovis people.
The Daily Mail has the story and photos here;
Mike Ruggeri's Pre-Clovis and Clovis World
Mike Ruggeri’s Pre-Clovis and Clovis World Magazine
Mike Ruggeri’s Pre-Clovis and Clovis News on Tumblr