We keep tabs on California campgrounds, roughly 25,000 individual campsites, checked every few minutes around the clock. What follows is an explanation of what we measure, how we measure it, and what the numbers in our guides are actually telling you.

What we check

Two reservation systems cover nearly all bookable public camping in California, and we watch both: ReserveCalifornia for the state parks, recreation.gov for the national parks and forests. For each campground we track which sites are open on which nights the same thing you would see searching the booking site yourself, gathered on a repeating cycle.

What we record

Each day we save a snapshot per campground: weekend occupancy, midweek occupancy, and a sellout score that blends the two. Separately, whenever a booked site frees up again, we log that cancellation with a timestamp. Those two records are what feed our guides, the hardest campgrounds to book ranking included.

What the numbers mean

When a campground shows no open sites, that means sold out for the window we measured, not sold out forever. Cancellations reopen sites all the time, which is precisely why our alerts exist. A campground showing nothing at all might just be closed for the season. From outside the booking systems, closed and sold out look identical, so we publish no data rather than guess.

Using this data

The dataset grows daily and we are glad to share it. Journalist or researcher needing a custom cut, regional numbers, or more detail on the method? Reach us at campsitescan.com and we will pull it for you.