From jct Glacier National Park Rd & US 2: Go 6 mi W on US 2.
The sites were very close together. The bathrooms weren't well kept. There was no toilet paper in the morning. The train came by multiple times throughout the night and blew its horn which woke us up each time. The tent sites aren't very flat/even. We reserved a site far in advance and they gave it away to someone else. The manager gave us an option of two sites. One site didn't even have its own picnic table. The only upside is that it is very close to the W. entrance of Glacier.
People have some valid concerns with Sundance. Trains, small sites, bathroom issues. Yes, there are trains that goes by even in the middle of the night with loud horns. They aren't super close, but close enough that they might wake you up. Same is true for every location withing quite a radius. It is just the nature of the area. Our site wasn't small, but we were close to neighbors. No issue. Friendly people and never an issue. Welcome to camping. Bathrooms - mixed bag. Showers were good, toilet space was right and there was a lack of soap. Otherwise, the site was nice. It was convenient. People were friendly. We were really happy here and would come back here without question.
We tent camped here for a week while exploring the Glacier area. Loved having electric and water right at site. Most of the campground is shady and had minimal bugs. Loved that there were easily accessible trash cans throughout and a dish washing station. Ice and firewood was reasonably priced. We had Verizon coverage but the advertised wifi was non existent. Would stay here again!