The Car Craft Summer Nationals is Friday July 18th through Sunday July 20th at the Minnesota State Fairgrounds.
http://www.familyevents.com/event/285
This event is open to just about all cars and typically pulls in over 6000 vehicles.
Tickets are $13 in advance at O'Reilly Auto Parts stores or $15 at the gate.
If you want to show your car, advance registration is $45 for all three days up to July 14th or $65 after that.
I'll be there Saturday only this year.