Within the U.S., what area lacked cities of 100,000+ after the civil war?

Question

Anyone know of a well-populated region in the U.S. that didn't have large cities..?

Answer 1

The total population of the United States in 1870 was 38.5 million people. So most of the country did not have major cities at that time. Primarily the East Coast (Boston, NYC, Philadelphia) and Midwest (Detroit and Chicago).

The west was largely vacant at the time (with the exception of the folks who originally settled it), and many states were not yet states (Arizona, Colorado, Idaho, Montana, New Mexico, North and South Dakota, Oklahoma, Utah, Washington, Wyoming -- all territories in 1870).

So that rules out "well-populated" since the west wasn't.
New Mexico has 92,000 people total, and it was the largest.

The Census of 1870 is broken down by county, so you should be able to find your answer here:
http://www2.census.gov/prod2/decennial/documents/1870a-05.pdf