Question: Laton Alton Huffman was an American photographer who worked at an Army post  situated on the south bank of the Yellowstone River, at the mouth of what?
Sentence (from "Fort Alexander, Manitoba"): During the fur trade era, La Vérendrye built a trading post, named Fort Maurepas, on the north side of the river; this post was abandoned near the end of the French period.
Relevant evidence: No