Md to South Dakota in July travel help

Can't help you with the PA route. However, we went from Cleveland to Rapid City last August via I-90 except around Chicago where we tried to bypass the city traffic via I-94/I-294. The Chicago bypass route was PACKED FULL of traffic and a lot of inconsiderate drivers even on a Thursday morning between 10 AM and 3 PM. If you do the bypass, you may want to plan your drive around Chicago for a Sunday morning and be sure you have a GPS on board so that you don't get in the wrong lane for a turn-off. Also, that bypass route is an EXPENSIVE$$ toll road with toll booths about every 10 miles. I STRONGLY RECOMMEND that you get yourself an EZ-Pass or I-Pass transponder to avoid a 5 minute stop at each toll booth. Side road toll booths may not be manned and will require the correct cash toll or a transponder. If you miss a turn-off, doing a U-turn at the next exit could be VERY EXPENSIVE. On our return trip, we drove down through Peoria and Indianapolis to avoid Chicago traffic and tolls.

I hope your plans include a week or two in the Black Hills area - It's a really nice place to visit.