I spent 40 years driving semi's coast to coast and all around and through St Louis, MO on the way to Kansas and points west and that is the way to go although I 155 N to I 270 W to I 70 W is a little faster, by about a minute unless you get backed up in traffic for some reason . If you want to see downtown SL go I 64 - I 70... (FYI) If you are going through... Kansas City...I 70 TO I670 back to I 70 in Kansas and you will be about 10 minute's ahead of any one who stayed on I 70 at the split when you cross into Kansas and much less zig zagging. Have a good trip.