Sold out? What to do next

Summer weekends at Watkins Glen, Assateague and Cape Henlopen can go within minutes of opening. The National Park Service says nearly all Assateague weekend dates fill on the first day. Missing the release isn't the end: people cancel, and those sites go back on the booking system one at a time.

1. Set a cancellation alert

Start with Campflare, which is free and sends email or text alerts when a site opens up. If you want more frequent scans and text alerts, Campnab is a paid option.

For the National Seashore campgrounds at Assateague, Recreation.gov also has its own free availability alert on each campground page.

2. Try the other Assateague

Assateague has two separate campground systems: Maryland's state park books 365 days ahead, and the National Seashore books 6 months ahead on Recreation.gov. If one is full, check the other.

3. Check the minimum-stay rules

Minimums decide what's left: Maryland needs 2 nights from Memorial Day weekend through Labor Day (3 on holiday weekends), and Cape Henlopen needs 2 on weekends. New York says some parks allow 1-night bookings 3 to 7 days before arrival. A single weeknight can be easier to find.

4. Stay nearby instead

Each campground page has a lodging map and, where we've checked them, private campgrounds nearby.

• Watkins Glen State Park: Watkins Glen, NY (Finger Lakes)
• Letchworth State Park: Castile, NY
• Assateague State Park: Berlin, MD (near Ocean City)
• Assateague Island National Seashore (NPS campgrounds): Berlin, MD (Maryland district)
• Cape Henlopen State Park: Lewes, DE (near Rehoboth Beach)
• Ricketts Glen State Park: Benton, PA
• Hither Hills State Park: Montauk, NY
• Fish Creek Pond Campground: Saranac Lake, NY (Adirondacks)

What never works

Booking bots and resellers. State reservation systems ban automated booking, and a resold permit can be cancelled. This site never books for you and never checks booking sites automatically.