We see this a lot in Atlanta because most people "ain't from around here." They move here as short term corporate transfers, and if the interstates back up they have no idea what to do. The radio stations try to help, but if you don't know the names of the back roads it isn't much help.
We usually take to the back roads when we're visiting family on big holidays and the interstates back up. It usually works pretty well.
For those of you who are not familiar with HOUSTON. Their traffic is always bad.. this is just extra bad... but on 45 the contra is open at 1488- 125 miles to Buffalo TX