As 60 Russian officials get expelled from the United States this week, consider this 1957 map produced by the State Department, via the Library of Congress. It shows how, at that time, about a third of the U.S. was off limits to Russian visitors. Among the red patches marking banned travel, the green circles mark the cities where Soviet and Eastern bloc citizens could legally go. So why could Cold War travelers go to Nashville but not Memphis? National Geographic has a theory that the seemingly arbitrary “red lines” may have been a way to hide the conditions of Jim Crow.