Free! No parking fees either!
The main parking lot at the Visitor Center is free because it is technically a wayside rest. If you drive into the park towards the lakeshore, you will need a MN State Park Vehicle Permit. Those are $7/day or $35/year and good for all MN State Parks.
I assumed you needed a State park pass (which we bought because it was needed at Grand Portage), but I think Rob is right, because there was no pay station in route & no pay box (because I looked).
If you want to park by the lake front its $7 for a day pass.
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