May: Bison calves, prairie dog pups and green badlands. Late spring is when the North Dakota badlands look most alive, and summer crowds haven't arrived.
Permits and reservations
An entrance fee is required year-round, but the park does not issue timed-entry permits.
Backcountry camping permit: Camping outside the developed campgrounds needs a free permit, issued at the South Unit Visitor Center in Medora (South Unit and Elkhorn Ranch) or the North Unit Visitor Center. Permits are not issued at Painted Canyon.
Campgrounds: Cottonwood (South Unit) campsites and the group sites at Cottonwood, Roundup Horse Camp and Juniper (North Unit) can be reserved on Recreation.gov or by phone at 1-877-444-6777.