We track live availability at 36 campgrounds with group campsites in Montana, across 24 towns. Group sites are booked further ahead than anything else — reunions, scout troops and weddings plan a year out — and there is rarely more than one or two per campground. A cancellation on a group site frees up a whole weekend for a whole party, which is why they do not sit unclaimed for long.
Booking goes through Recreation.gov. Searching is free.