We run from Chicago to Boston every year to visit our daughter. I endorse taking the Mass Pike to the Thruway on your first leg. I've stayed at the Erie KOA, and also at an another KOA about 40 miles up I90 at Westfield NY which is closer to the highway, both are nice overnight stops.
Going through Cleveland, we take the bypass. To you that would be from I90 to I271 to I480 and then I80. Its about the same time as going through town, but a lot less exciting without the S curves.
The worst part of the trip is the Borman Expressway (I80) around Gary Ind, it can be like the last lap at Talledega in a NASCAR race. It has been widened which improved things a lot but you better be paying attention from I65 to Joliet. Just keep up with traffic and follow the signs to Iowa. If the locals cut in front of you, God bless them, reset your gap and keep on rolling.
From there it's clear sailing all the way to SD. Have a great trip!
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