Upper Sioux Agency State Park

Yellow Medicine campground at the Upper Sioux Agency State Park is a lovely campground. Not much shade, but tall grasses and a few trees here and there provide a little bit of privacy. I stayed here one night in June 2017, at Yellow Medicine campground site 28e. 30A electric tested and worked fine. There's some highway noise, but it's not too awful, as the highway isn't traveled too often. I'd say I maybe heard a vehicle every 5-10 minutes when it was busy, otherwise rarely.

There's lots of hiking trails and lookouts here, plenty to do for a few days. It's about 12 minutes to Granite Falls which has some stuff, 40 minutes to Marshall which is a little bigger of a town, or a bit over two hours to get to the Twin Cities metro area.

One thing to keep in mind: there are, I believe, three entrances to things in the park. There's the horse campground, the main entrance, and then the campground entrance. If you're in an RV, make sure you don't continue down the small road in the main area (it's for the viewpoint, not campground) because it might get tough to pass someone (I made this mistake, but it was fine). The campground is a little bit further east.

Cell service at campsite, unboosted:

AT&T - three bars LTE, 107ms ping, 10.51mbps down, 4.12mbps up, plenty reliable

Verizon - one bar 1x extended. On occasion, 3G. Completely unusable. Some parts of the park have LTE.

T-Mobile - two bars LTE - I got 63ms ping, 9mbps down, 0.56mbps up. Though, not quite as reliable as AT&T. On occasion, it faded to three bars extended (E).