Final answer:
The thickest crust in the central U.S. is likely found in the region with the highest elevation, such as the Rocky Mountains.
Step-by-step explanation:
The topographic profile across the central U.S. can give us an idea of the relative thickness of the crust in different regions. Based on the information provided, we know that the continental crust is thicker than the oceanic crust, with an average thickness of 20 to 70 kilometers. Therefore, the region in the central U.S. with the thickest crust would likely be the one with the highest elevation, such as the Rocky Mountains. These mountains are composed of thick crustal rocks, which contribute to their towering peaks.