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 ...

By 1845, Texas had been annexed to the United States, followed by a large swath of western land in the Treaty of Guadalupe Hidalgo in 1848. Click on the map to reach a zoomable version ...