Check out the Atlas of the Historical Geography of the United States!
There is an amazing set of maps at the University of Richmond’s Digital Scholarship Lab that show the geographic progression of issues in American/U.S. history. For example, you can track the abolition of slavery from 1800-1865, or the growth of colleges and universities from 1775-1890.
These maps are invaluable for showing the concrete steps different movements, reforms, laws, and more had to take to become reality—steps that are all too often ignored in favor of descriptions like “abolition swept the north” or “the right to vote was granted to some American women before 1920.” If you want to know—to see—how ideas progressed, what we call “historical geography”, check out the Atlas.