Excluding parks with fewer than 100,000 annual visitors, primarily because I think this makes the quiz more interesting.
For reference, those excluded parks are: Gates of the Arctic, Kobuk Valley, Lake Clark, Isle Royale, North Cascades, Katmai, Dry Tortugas, Wrangell-St. Elias, and American Samoa.
American Samoa 2,080
Dry Tortugas 207
North Cascades 15
Isle Royale 12
Katmai 2.5
Kobuk Valley 2.2
Lake Clark 2.1
Wrangell-St. Elias 2.0
Gates of the Arctic 0.4