The U.S. Coast Survey map calculated the number of slaves in each county in the United States in 1860. Library of Congress In September of 1861, the U.S. Coast Survey published a large map ...

The United States still has remnants of its colonial empire, for example, Puerto Rico, Guam, the Commonwealth of the Northern Marianas, American Samoa and the U.S. Virgin Islands.

All maps credit Charles O. Paullin, Atlas of the Historical Geography of the United States(1932), via By 1930, three days brought us 2,500 miles. In 1800, three days would have taken us just 250 ...