Confederate States 43,435,315
Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, N Carolina, S Carolina, Tennessee, Texas, Virginia
Union Slave States 12,765,371
Delaware, Kentucky, Maryland, Missouri, W Virginia
Total population above combined states, 196056,200,686 or 31.3%
Total population, other 34 states & District of Columbia123,152,489
Now, the reason for putting these numbers down like that is to tackle a widespread but erroneous perception (or two) and put something more in line with the facts in its place.
16 states = 32 Senators representing 31.3% of the total population of the country, so there isn't a disproportionate amount of House of Representatives votes going to the southeast quadrant of the country, either, the way there is with California or New York where there's a lot more people.