The checklist

Start with the parks you know.

Most park people undercount. Was Indiana Dunes after it became a National Park? Did that Ohio stop include Cuyahoga Valley? The checklist settles it.

ParkRank's picker is a visual checklist of all 63 U.S. National Parks — photo tiles, most-visited parks first, searchable by park or state. Tap everything you've been to and watch the counter climb. Most people land somewhere between 5 and 15; the truly afflicted push past 40.

Then do something with it

A count is trivia. The interesting part is what your list says: once your visited parks are checked, rank them head-to-head and find out what your actual #1 is — then see whether the crowd agrees.

Your checklist stays on your device between visits, so you can update it after every trip.