How Much Reservation Data It Takes to Trust an Odds Score

A campground gets a Campsite Odds score only after its reservation history clears two thresholds: at least 6 fiscal-year/month rows of reservation history in total, and at least 30 merged reservations for the specific month being scored. Fall short of either bar, and there's no score — and no page — for that campground or month.

Key takeaways:

• A campground needs at least 6 distinct fiscal-year/month rows of reservation history — roughly one full camping season — before it gets scored at all.
• Even a campground that clears that bar only gets a score for a given month if that month has at least 30 merged reservations; thinner months are skipped.
• Scores blend up to the last 3 fiscal years of data, weighted 50% for the most recent year, 30% for the year before that, and 20% for the year before that.
• If a campground or month doesn't clear these bars, there's simply no page for it — Campsite Odds never shows a guessed or padded number.
• The exact formula behind every score lives on the methodology page; where the underlying reservation counts come from is documented on data sources.

Why it takes two data gates, not one

The first gate looks at the whole campground: does it have at least 6 distinct fiscal-year/month rows of reservation history on record? That's roughly the equivalent of one full camping season's worth of records, and it's deliberately lenient about campgrounds that close for part of the year — a campground that only operates May through September isn't penalized for the months it's shut. What the gate rules out is a campground Campsite Odds has barely seen: one or two scattered reservation records aren't enough to say anything reliable about how hard it is to book.

The second gate is stricter and more specific. Even after a campground clears the first bar, each individual month still needs at least 30 merged reservations before it gets its own score. A campground can be well-established overall and still have a slow shoulder-season month that hasn't logged enough bookings yet — in that case, that one month gets skipped while the rest of the campground's calendar is scored normally. This is also where reservation systems matter: a lottery-run campground and a first-come, first-served one accumulate bookable records differently over a season, which is worth understanding on its own — see Camping Lottery vs. First-Come, First-Served.

Both gates exist for the same reason: a booking-difficulty score is only useful if it's built on enough real bookings to reflect an actual pattern, not noise from a handful of reservations. Day-of-week patterns — the kind covered in Why Weekends Book Faster Than Weekdays — don't change whether a month clears these gates; a weekday reservation counts the same as a weekend one toward the 30-reservation minimum, they just need enough of them, of any kind, before the month qualifies. Once a campground/month clears both gates, What Campsite Odds' Booking-Difficulty Score Actually Means walks through the four components that turn that reservation history into a 1–10 score. This post is about the step before that — what has to be true before any score gets computed at all.

How the 3-year recency weighting works

Once a campground/month has enough data to be scored, Campsite Odds doesn't treat every year of history equally. Scores blend up to the last 3 fiscal years, weighted 50% for the most recent year, 30% for the year before that, and 20% for the year before that. If a campground only has 1 or 2 years of usable history so far, the weights are renormalized proportionally across whatever years exist — a newer campground isn't penalized for not having a third year yet, it's just scored on what's actually there.

This weighting has a practical effect: a campground's score moves as new seasons of bookings come in. A month that got noticeably harder to book last year — the kind of shift covered in The 4 Campsite Sellout Speeds, Explained — pulls this year's score toward "harder," while an older, less representative season fades in influence rather than disappearing outright. Reservations accumulate against a campground's booking window as the season approaches — see How Recreation.gov's Booking Window Actually Works for how that timing works — and each fiscal year's worth of those bookings becomes one input into the blend described above.

What it means when a campground/month has no page

Because a page only exists when there's a score behind it, "no page" is itself informative: it means that campground/month combination hasn't cleared the 6-row or 30-reservation bar yet, not that Campsite Odds forgot about it or that the campground is easy to book. A brand-new campground added to Recreation.gov this year, or one that rarely gets reserved at all, may simply not have a page yet — and that's intentional. Showing a score built on three or four bookings would be worse than showing nothing, because it would look precise without actually being reliable.

Pages that do exist show their work. A page like upper-pines-campground-ca in July, or devils-garden-campground-ut, or cottonwood-campground-ca, shows its own "Based on N years of reservation data" line right under the score — so a reader isn't taking the number on faith. If the campground/month you're looking for doesn't have a page, that's a signal to look at nearby alternatives instead: How to Find an Easier Campsite When Your First-Choice Park Is Sold Out, or the broader lists on easy to book in July and states, are better starting points than guessing.

How to check how much data backs a specific score

Every campground/month page carries its own data-year count, right next to the score itself, so you never have to take a number on faith. Reading that line alongside the rest of the page — including a lead-time chart, where one is shown — gives you a fuller picture of what the score is actually built from; see How to Read a Campground's Lead-Time Chart for how to interpret that chart specifically.

Here's how to sanity-check any score you see:

1. Open the campground/month page and find the "Based on N years of reservation data" line under the score — a higher N means the number is backed by more history, and a low N is worth a little more caution.
2. If there's no page at all for a campground or month, read that as "not enough reservation history yet," not "this campground must be easy."
3. Check data sources to see exactly where the underlying reservation numbers come from.
4. Compare nearby months on the same campground's page — real seasonal patterns move gradually across a calendar; they don't look like a single unexplained spike.

The two data gates, the recency weighting, and the "Based on N years" line are all part of the same idea: don't show a number unless there's enough real history to trust it. For the full formula behind every score, see methodology; for where the reservation counts themselves come from, see data sources; and for who builds and maintains all of this, see about and Sharon Ben-Moshe's author page.

Frequently asked questions

What's the minimum amount of reservation data before a campground gets a score?

A campground needs at least 6 fiscal-year/month rows of reservation history in total before it's scored at all, and each individual month needs at least 30 merged reservations before that month gets its own score. Both bars have to clear before a campground/month page exists — if either one doesn't, there's no score and no page for it.

Why do some campground/month pages not exist at all?

Because Campsite Odds only publishes a page when there's an actual score behind it. If a campground/month hasn't cleared the 6-row or 30-reservation minimum, the page simply isn't built for it yet — showing an unreliable guess would be worse than showing nothing. If your first choice doesn't have a page, How to Find an Easier Campsite When Your First-Choice Park Is Sold Out covers what to look at instead.

Does a brand-new campground ever get a score right away?

Not immediately. A campground needs roughly one full camping season's worth of reservation history — at least 6 fiscal-year/month rows — before it clears the first data gate. Campgrounds that close for part of the year aren't penalized for those closed months; the gate just needs enough history from when the campground is actually open and taking reservations.

Do cancelled reservations count toward the 30-reservation minimum for a month?

The 30-reservation bar counts merged reservation records for that month overall. How a specific cancelled site gets reopened and rebooked is a related but separate mechanic — see What Happens to Cancelled Campsites (and How to Get One) for how that part of the system works.

Why does Campsite Odds weight recent years more heavily than older ones?

Because booking difficulty changes over time — a campground can get more popular, less popular, or shift its capacity, and older seasons become less representative of what booking it looks like today. Weighting the most recent fiscal year at 50%, the year before at 30%, and the year before that at 20% keeps scores responsive to recent patterns without discarding older history entirely.

Where can I see how many years of data back a specific score?

Every campground/month page shows a "Based on N years of reservation data" line directly next to its score, so you can see for yourself exactly how much history backs that specific number before deciding how much weight to give it.