Glossary
Plain-language definitions of the terms used across Trailhead Timing.
- Access Pass
- A free lifetime America the Beautiful pass for US citizens and residents with a permanent disability.
- America the Beautiful pass
- The interagency pass covering entrance and standard day-use fees at federal recreation lands. In 2026, $80 for US residents and $250 for nonresidents. Read more
- Civil twilight
- The period when the Sun is between the horizon and 6° below it. After it ends, artificial light is normally needed outdoors. Read more
- Fee-free day
- A date when NPS sites that charge entrance fees waive them. From 2026, for US citizens and residents only. Read more
- Heat exhaustion
- Illness from dehydration and heavy sweating, with fatigue, nausea, cool moist skin, headache and cramps. Read more
- Heat stroke
- A life-threatening emergency in which the body can't cool itself; marked by confusion or altered mental status.
- Hyponatremia
- Low blood sodium from drinking a lot of water while losing salt through sweat. Eat salty food with water.
- Nonresident fee
- A $100 per-person charge from 2026 for non-US residents aged 16 and over at 11 national parks, on top of the entrance fee. Read more
- Park annual pass
- A 12-month pass for one park or park group, such as the Southeast Utah Parks pass for Arches and Canyonlands.
- Parking tag
- Required at Great Smoky Mountains to park more than 15 minutes; $5 daily, $15 weekly or $40 annual. Passes don't replace it.
- Per-person fee
- An entrance fee charged to each person 16 and over, for people entering on foot or bicycle, or at parks that charge only per person.
- Per-vehicle fee
- An entrance fee covering one private, non-commercial vehicle and everyone in it.
- Recreation visit
- The NPS's standard count of people entering a park for recreation, published monthly on its Visitor Use Statistics site. Read more
- Recreation.gov
- The federal booking site for reservations, timed entry and digital America the Beautiful passes.
- Senior Pass
- An America the Beautiful pass for US citizens and residents aged 62 and older, $20 a year or $80 for life.
- Shoulder season
- The months just before or after a park's peak season, often quieter while most facilities are still open. Read more
- Southeast Utah Parks pass
- A $55 annual pass valid at Arches, Canyonlands, Natural Bridges and Hovenweep.
- Standard pass
- A park's regular entrance pass for one visit, valid for up to 7 days at most parks. Read more
- Timed entry
- A reservation system some parks use to manage vehicle traffic at busy times. Its fees are separate from entrance fees.
- Turnaround time
- The latest time to start back on an out-and-back hike so you return before your planned back-by time. Read more