Boone County Fairgrounds just north of town on Rt 76. This is a 2 day show, best time for swap meet stuff is on Saturdays, on Sunday the car show is on and most of the swappers are gone. I will probably be going there with one of my Ks, unless we have really bad weather.
This is a very old and established show that is sponsered, as always, by the Model T Club. Food, music, etc etc..
Belvidere is real close to the Wisconsin/Illinois border, check on the map for more
HUGE annual Lions Club show this fall in Beloit Wisconsin, more details later this summer