- Alibates Flint Quarries National Monument: Road Construction Work to begin May 4-Oct 24, 2026
- Acadia National Park: Several Trails Close For Peregrine Falcon Nesting Season
- Adams National Historical Park: Intermittent Visitor Center Phone Issues
- Acadia National Park: Avoid Water Contact at Sand Beach Lagoon (Not for Sand Beach)
- Agate Fossil Beds National Monument: Limited Cell Phone Coverage
- Alcatraz Island: Hospital wing, dining hall, shower room closed for rehabilitation work
- Alcatraz Island: Auto-Theft Warning - Only Bring What You Need to the Park
- Allegheny Portage Railroad National Historic Site: Staple Bend Tunnel Closure
Source: NPS