Well, a lonnng drive indeed there guy.
I drive from Milwaukee to N.Y. 5 times a year and I seem to average about 70mph the whole way, and that takes a little over twelve hours, maybe twelve and a half.
I just checked YOUR trip on mapquest and it tells me its less distance than my trip to NY, and it tells me the trip from Chicago to MS would be 12 hours exactly, but account for traffic, it will be more like 12.5