I haven't seen details on how First Come First Serve (FCFS) camping works, so here goes, based on our experience. We arrived at Many Glacier on Thursday Aug. 24 at 5:45 am. There were already 20+ cars/bikes in line, and we were about 5 cars too short; the official campground fill time that day was 7:51 am and they told us about 7:30 we were out of luck. The next day, fill time was 10:31 am, so you never know, but early means EARLY; we know of others who arrived around 6:00 am on other days and it was too late for them to get in.

FWIW, Rising Sun is a good alternative that TENDS not to fill so soon. We arrived there at 5:55 am on Friday Aug 25, and I was first in line. The ranger assigned me a site by 8:00 am. The site assignment was delayed because they were relocating tent campers from St. Mary due to bear activity--which overall reduced the number of available sites for FCFS campers. I know there were people in line behind me who did not get in; I believe there were approximately ten sites for FCFS campers that morning. Official check out time is Noon, so you might have to wait until people vacate the site before you can occupy it, but what I observed is that most people clear out early, by 7 or 8 am.

Once you snag a FCFS site, you can stay as many days as you want (within the total 14 days allowed in the park). You can also decide day by day: we started with a two day reservation at Rising Sun, and added one more day (the rangers need to know by early morning of the day you leave so they can assign the site to whoever shows up in line).

I understand that other campgrounds in Glacier with FCFS sites do not use the wait-in-line system, and you have to drive around until you find a site. Yuck. A ranger told me there were people knocking on doors at 2:00 am asking if people were leaving. I MUCH prefer the wait in line system, seems fairer, easier, much less annoying and invasive.

Yeah, so this review is for Many Glacier and we didn't actually stay there, couldn't get in. I heard that sites in Many Glacier are more crowded together than at other campgrounds, sort of looked that way to me when we were walking around while waiting to see if we could get in . Rising Sun and St. Mary were both quite satisfactory for us.

We are a family of six (two adults, four kids ages 8-14). We arrived at our Many Glacier campground very disappointed to see a most inadequate space we had been assigned. It would be impossible to set up both our tents without them being on top of the plants encroaching on the sight, and it left no room for preparing food.
We approached the campground host to ask for assistance. His (name was Rich) response was "I have no solution for you". We looked around at the several other campsites , not yet being utilized, that would have suited us better and wondered why something couldn't be done. We we're all feeling very let down , and a little frustrated that there was no effort to help create a better experience. Rich came by on his bike and agreed the campground was too small for us but still offered no solution. It was only when my husband asked if we could switch with the campsite across the lane labeled "admin" that Rich agreed we could do that. We then moved and that campsite was much better. Later we watched as two other sets of campers struggled with securing their sites as well, despite having reserved in advance. They were told to leave one or two of their chairs to secure their site, and we intervened when one set of chars was almost stolen.
The rangers that ran the evening program we're fantastic and provided a great talk, especially Monica. Sarah at the ranger station was exceptional as well in swearing our daughter in as a junior ranger.
Our kids loved the ice cream at the motor lodge store! Lots of wildlife too (bear, moose, birds).
In summary, campground was fine, administration of it was poor. We made the best of it and enjoyed our time here

I loved this campground! Doesn't seem like there are a lot of "bad" spots. Nice pull in spots for campers, private sites, nice clean bathrooms. BUT the nicest thing is that you are so close to the camp store which sells EVERYTHING but specifically firewood (until 10pm) and coffee for those mornings when you are feeling lazy. There are also informative ranger led talks in the evenings. Very close to numerous trail heads.