itOpened Blog · Cancellation Data
Mather Campground, Counted
Mather is Watchman's mirror image. Grand Canyon's South Rim campground produced 373 confirmed openings since Oct 29, 10:54 PM ET — a large flow by any standard in this log — and then did the opposite of recycling quickly: across 164 completed cycles, a Mather opening survives a median 28h 20m before someone books it. That is the slowest median survival of any campground in our log with at least a hundred completed cycles — the next slowest, at 16h 35m, is not close. The coverage is broad, too: the openings come from 178 distinct campsites, more than half of the 327 sites Recreation.gov lists at Mather — a campground it calls the largest in the National Park Service system. One canyon-edge campground, counted: big flow, slow clock, and a hunting style that follows from both.
Quick answers
- How many Mather campsite openings are there?
- 373 confirmed openings at Mather Campground since Oct 29, 10:54 PM ET — from 178 distinct campsites, for stays 2026-11-01 – 2026-12-30.
- How long do Mather openings last?
- Longer than anywhere else at scale: a median survival of 28h 20m across 164 completed cycles — the slowest median of any facility in our log with 100 or more completed cycles. The next slowest such median is 16h 35m.
- How many sites does Mather Campground have?
- 327 campsites, per Recreation.gov — which calls Mather the largest campground in the National Park Service system, with seven large group sites among them. Our log has recorded openings from 178 of the 327.
- When are Mather reservations recommended?
- Recreation.gov recommends reservations in peak season, March 1 through November 30, and they can be made up to six months in advance. Our watch window covers the end of that season — and its openings surface at a median lead of 5 days.
Watch it with itOpened
Mather openings wait a full day — if you know they exist.
Mather Campground produced 373 confirmed openings in twelve days of watching — from 178 of its 327 sites, surviving a median 28h 20m. Our scanners poll it around the clock and text you when the next opening confirms.
Proof, from our own scanners: 373 confirmed openings at Mather since Oct 29, 2026 — each one re-verified before logging. See the live cancellation index.
Watch Mather openingsFree to start. We never book, hold, or resell — you book it yourself, in your own account, at the normal price. Fees pay for monitoring; openings are first-come and cannot be guaranteed.
The measurement, in one block
Headline: 373 confirmed openings at Mather Campground from 178 distinct campsites; median lead 5 days; median survival 28h 20m across 164 completed cycles — the slowest median of any facility in the log with 100+ completed cycles (next: 16h 35m); single nights 184 (49.3%); stays of 3+ nights 85 (22.8%).
As of Nov 11, 05:38 AM ET — measurement window Oct 29, 10:54 PM ET – Nov 11, 05:38 AM ET (Eastern); stays 2026-11-01 – 2026-12-30.
Method: confirmed openings from the production alert log (each re-fetched and verified before logging), filtered to Mather Campground; survival from the closure log's completed, unambiguous life cycles for the same facility, ranked against every facility with at least 100 completed cycles in the same log; lead = stay start date minus detection date (Eastern).
The single-campground table again — set beside its mirror image in Zion:
| Campground | Confirmed openings | Distinct campsites | Median survival |
|---|---|---|---|
| Mather Campground | 373 | 178 | 28h 20m (n=164) |
| Watchman Campground (Zion) | 758 | 167 | 2h 05m (n=603) |
Mather is the South Rim's campground, in Grand Canyon Village a short walk from the rim, under ponderosa pines at roughly 7,000 feet. Recreation.gov lists 327 campsites and calls it the largest campground in the National Park Service system; it recommends reservations from March 1 through November 30, bookable up to six months in advance, with a small block of first-come sites sold at the kiosk in season. Our watch covers the campground through the end of that reservation season, and the flow it records is the season's tail being handed back: 373 openings, from 178 distinct sites, for stays running 2026-11-01 – 2026-12-30.
The slowest big clock in the log
The survival column is the story. At 28h 20m across 164 completed cycles, Mather's median opening is still bookable a full day after it surfaces — and it holds the slowest median of any facility in this log with at least 100 completed cycles, well clear of the next slowest at 16h 35m. Two slower medians exist in the log, at island and small campgrounds with sample sizes in the fifties; at Mather's scale, nothing else waits this long. The labelled interpretation has two plausible parts, and the data cannot separate them: November at the South Rim is cold — rim nights run below freezing — so the pool of hunters for a specific November night is thinner than Zion's; and with 327 sites, a dropped Mather site competes with near-identical neighbours, so no single opening is scarce. What is measured is the outcome: a hunter who checks once a day at Mather is fishing the median, not the tail.
Ordinary flow, extraordinary patience
Everything else about Mather's flow is standard-issue, which is what makes the clock stand out. The median lead is 5 days; 58 openings were same-day; 184 are single nights (49.3%, against 55.3% system-wide) and 85 (22.8%) run three nights or longer. The deepest stay dates — Nov 07 (31); Nov 06 (27); Nov 08 (25) — are the first week of November, the season's last full days being set and unset. No cliff, no wall: a six-month window shedding ordinary cancellations, at an extraordinary pace of re-booking.
What this means for a hunter
Mather rewards the organised hunter over the fast one — the opposite of Watchman, counted alongside this post. At a 28h 20m median, a morning alert is usually still an evening opportunity, and a daily manual check has an honest chance; the watch still wins, because it sees the opening the moment it surfaces rather than the next morning, but it wins on convenience here, not on seconds. The better edge is selection: with openings surfacing from 178 different sites, hunters can afford to be choosy about loop and site rather than grabbing the first fragment — pass on the wrong site and the flow, at 373 openings in twelve days, will offer another.
The limits, plainly
The window is twelve days at the end of the reservation-recommended season, in the cold shoulder — summer Mather, with the rim full, may recycle far faster, and this log cannot say. The 'slowest' ranking is computed over facilities with at least 100 completed cycles and is stated that way everywhere it appears; smaller facilities with slower medians are named in the method, not hidden. Survival medians rest on completed cycles only (164 at Mather). Desert View and the North Rim campground are separate facilities and are not in this count. What survives the caveats is the clock: 373 verified openings, and a median wait of 28h 20m before anyone takes them.
Watch it with itOpened
Mather openings wait a full day — if you know they exist.
Mather Campground produced 373 confirmed openings in twelve days of watching — from 178 of its 327 sites, surviving a median 28h 20m. Our scanners poll it around the clock and text you when the next opening confirms.
Proof, from our own scanners: 373 confirmed openings at Mather since Oct 29, 2026 — each one re-verified before logging. See the live cancellation index.
Watch Mather openingsFree to start. We never book, hold, or resell — you book it yourself, in your own account, at the normal price. Fees pay for monitoring; openings are first-come and cannot be guaranteed.
Frequently asked questions
How many campsites does Mather Campground have?
327 campsites, per Recreation.gov, which calls Mather the largest campground in the National Park Service system. Our log recorded openings from 178 of them in twelve days.
Do you need reservations for Mather Campground?
Recreation.gov strongly recommends them in peak season, March 1 through November 30; reservations can be made up to six months in advance. A limited number of first-come, first-served sites are sold in person at the campground kiosk in season.
How long do Mather cancellations last?
A median 28h 20m across 164 completed cycles in our log — the slowest median of any facility we measure with at least 100 completed cycles.
When do Mather openings appear?
At a median lead of 5 days before the stay, spread across the calendar with no release cliff; 58 of the 373 openings in our log were same-day.
Sources
- itOpened production scanner alert log (engine/alerts.jsonl), Oct 29, 10:54 PM ET – Nov 11, 05:38 AM ET: 17,389 confirmed openings in total, 14,987 excluding Cape Point Campground's 2,402 rolling-release alerts. Mather Campground: 373 openings (2.5% of the non-Cape total) from 178 distinct campsites; median lead 5 days; same-day: 58; single nights 184 (49.3%); 3+ nights 85 (22.8%); deepest stay dates: Nov 07 (31); Nov 06 (27); Nov 08 (25); system-wide single-night share 8290 of 14,987 (55.3%). Watchman figures in the comparison table: 758 openings, 167 campsites, survival 2h 05m (n=603). All figures computed from the log at build time.
- itOpened scanner closure log (engine/closures.jsonl), sample closing Nov 11, 05:38 AM ET: completed unambiguous cycles — Mather n=164, median survival 28h 20m, the slowest median among all facilities with at least 100 completed cycles (next slowest: 16h 35m). Ambiguous records excluded; Cape Point excluded. Censoring note: completed cycles only — openings still live at build time are not in any median.
- Recreation.gov, 'Mather Campground' (recreation.gov/camping/campgrounds/232490; accessed 2026-11-10): 'Mather Campground is the largest campground in the NPS system, with 327 campsites, including 7 large group sites'; reservations recommended during peak season March 1 – November 30 and may be booked up to six months in advance; approximately 20 first-come, first-served campsites are available in person in season.
- itOpened, 'Watchman Campground, counted' (/blog/watchman-campground-counted/): the fast mirror image — same measurement window, opposite clock — tabulated beside Mather in this post.
- itOpened methodology (/methodology/): watch registry, two-poll confirmation standard, and watch window (stays from November 1, 2026 onward).
Every figure in this article traces to one of the sources above. If a number isn't sourced, we don't print it.
Last updated 2026-11-10.