What day and time of the day will you be driving through?
Right now there is a ton of construction going on and closures change sometimes daily.
Not knowing exactly when you will be coming through, I would suggest taking the southern route once you hit I-270 (which will turn into I-255) into IL and up to I-70. Yes, there is construction on I-255 a couple of miles before you turn onto I-55/70, but it's a lot less congested than going through the heart of StL.
If you have a "smart phone" there is an app you can download called "Beat the Traffic". It gives you traffic conditions (red, yellow, green lines as roads) that have been pretty darn accurate.
Doug
