Campground availability in Yellow Stone NP

Us out West wrote:
Isn't there a phone # on the website?

I could not find any that is why I posted here.

Most of the campgrounds are first come.
Get there early we found availability at a couple of campgrounds. We showed up at 6 am and waited in line. When they opened the office they assigned spots to those in line. Do not drive in and pick out a site and occupy it they will kick you out and you will go to the back of the line. Saw it happen!!
Have fun
Jesseannie

There are message boards at each entrance that show what campgrounds have availability. What the boards do not show are how many spaces are available and what they will accommodate. There are no phone numbers for the non reservable locations. The reservable sites are managed by Xanterra, who is the concessionaire for park lodging. Waiting in line for a site to open is not my idea of fun. I would make a reservation wherever you can get one and go from there.
There is no place in Yellowstone close to everything else, so where you stay is less important than getting the amenities you may need. Only Fishing Bridge has power and water, some other campgrounds have showers and dump stations. Some sites do not allow generators at any time, others have restrictions. Some locations are mosquito factories, some are densely wooded and some are very difficult to navigate with anything other than a small B or C. You trip is going to be much more enjoyable if you have done your homework.

The only CG that I have used as a "drive up" is Mammoth Hot Springs at the North entrance. I have had good luck if arriving before noon during mid June.
I make reservations for Madison and Canyon.
Your best chance of getting a "drive up" is going to be early in the morning. I have seen several RV's lined up just waiting for a site.

I doubt if a phone call is going to work.

Isn't there a phone # on the website?