This was the Poster Sawmill on Buckman Creek, north of town near that dip in the road (the link shows the area this year, 2015!). I know, there's not much water flowing there, but where else could it have been? This card was sent in 1912, so the pic was taken before that. It's interesting to follow the creek west all the way to Mud Lake and Skunk Lake, near Vawter. (Looks like they're the headwaters of the Platte River). The creek seems to start in the swamps about 5 miles east of Buckman...at least, the stream no longer has a name on the map as you go east. Take a look ☺.