Buy It at Your Very First National Park Entrance Booth ($80)
Simply pull up to the entrance ranger booth at your first U.S. National Park (e.g., Grand Canyon, Zion, Yosemite, Yellowstone, Everglades, or Rocky Mountain), pay $80 by credit card, and receive your physical card on the spot—valid for 12 full months for your entire vehicle.
Official sources & further reading
Rules, prices and schedules change. Confirm details here before you travel: