The weekend is full. The campground is not.

The share of the site-nights the agencies were offering that had been booked when the snapshot was read. The denominator is what was on offer, never the campground’s size: a 240-site campground running 40 sites in October is 100% booked when those 40 are gone, not 17%. Every night in this window sits inside the same four weeks, so the days are compared against the same weather and the same open inventory.

Busiest night Saturday at 52.2%, quietest Tuesday at 25.1%. Derived: booked site-nights divided by offered site-nights (Available plus Reserved), summed over every campground with a snapshot no older than 36 hours.

1,469 campgrounds have every site they are offering taken on Sat, Sep 12, and 1,084 of them have a site free on one of the four nights from Mon, Sep 14 to Thu, Sep 17. Counting only the campgrounds offering more than one site that night — a lookout or a single cabin cannot be half full — it is 790 sold out and 670 of those with room midweek.

That is the whole argument, and it is the reason this site exists in the shape it does. The campground is not full. The weekend is.

The twelve with the most sites on offer that Saturday, of 1,084. A midweek count larger than the Saturday one is not an error: the agencies put a different number of sites on offer on different nights, and each figure counts what was on offer that night. Every campground here links to its own thirty-night strip.

We do not know whether anybody slept there. recreation.gov publishes what is booked. It does not publish whether the party arrived, and no reading in this record can tell a full campground from a campground full of reservations nobody used. So this page never says no-show, never says abandoned and never says ghost camping. It says what was offered and what was taken, which is all the record carries.

The agencies do price the no-show, and that is quotable. 509 campgrounds carry no-show terms in the cancellation policy on their own recreation.gov record, and 148 of them carry this sentence word for word: “No-shows are assessed $20.00 service fee and forfeit the first night's rate.” The government charging for a no-show is evidence that a no-show happens. It is not a count of how often.

It is one reading a day, not a live feed. The recorder asks recreation.gov’s own availability endpoint what is open at every campground with a facility id and a booking link, once each morning at 11:10 UTC, and writes it down. Between that reading and this page, sites have been booked and cancelled. Nothing older than 36 hours is rendered anywhere on this site, so if the daily pass stops these numbers disappear rather than quietly ageing.

Open means one thing: the status “Available”. “Reserved” is booked. Everything else the API can say — Not Reservable, Closed, NYR — means the site was not on offer that night, and those nights are in neither number here. A campground shut for the season and a campground booked solid both read zero available, and treating them as the same thing is the single easiest way to publish a lie about camping.

Some campgrounds cannot sell out at all. The ones that take walk-ups have nothing to book and no availability API, so they appear nowhere on this page. They are the answer to it, and this weekend’s map is where you find the room that is left.