Clovis points have been found in Clovis, New Mexico (duh!) and in Virginia, along the banks of Chesapeake Bay. A polar projection overlaid with the maximum glaciation of the last Ice Age (ca. 18,000 BCE) will show the possiblity that people following the ice could have visited North America.

As for boats, I very much doubt that they weren't available, as dugout canoes or logs lashed together at the least.