Iron Range OHV Park
The Iron Range OHV Park is located just outside of Biwabik Minnesota, with camping connected to the park by trail at West Forty Campground, and Sherwood Forest Campground.
The OHV Park is a converted iron mine dump, and as such is a very red dirt that simply won't come out of your clothes, so keep that in mind.
It offers a large enclosed riding area where you cannot get lost, with well marked trails for every kind of off road use including rock crawlers, trucks, mudders, 4 wheelers, and dirtbikes and is open year round. The riding area is free and sponsored by the MN DNR, but you will need to have an offroad registration for the state (most states enjoy reciprocity with MN in this regard) and pass a sound test (administered on site).
There is also countless riding for 4 wheelers and dirtbikes on nearby and connecting trails, including Big Aspen Trail System just 30 miles away (north) that offers great scenic riding without too much difficulty (some rocky areas) and well marked trails, a great day diversion ride while up at the OHV Park. There are also many trails just outside the OHV Park, even just off the access road to the park (Enterprise Dr)