A Missouri River channel once curved through the western edge of Elk Point, creating the area now known as Heritage Park. On August 22, 1804, Captain William Clark recorded that the river bent east and lay within 3 or 4 miles of the Big Sioux River, noted abundant elk sign, and wrote that camp was made after passing a tree in the prairie on the starboard side beyond a sandy point. In 1937, 77-year-old Elliott Collins, in a historical thesis of Union County submitted to the University of South Dakota, recounted that Lewis and Clark camped that night by a lone tree on a point of land on the river's north bank, about half a mile south and a quarter of a mile west of the present site of the Elk Point water plant, on the Eli Wixson farm later owned by Charles Stickney, placing the campsite in Heritage Park. In 1858, a treaty between the United States and the Yankton Sioux opened the Dakota frontier to settlement, and a military supply route was established from Sioux City, Iowa, to Fort Randall, a new outpost 150 miles west on the Missouri River. Eli Wixson, a daguerreotypist, chose land 20 miles north of Sioux City on the Military Road where valley flatland appeared to escape high water from the Missouri and Big Sioux Rivers. In 1859, three years before the Homestead Act brought immigrant settlers into Dakota Territory, Wixson paid a $14 filing fee and $1.25 an acre to become Elk Point's first permanent citizen. He owned Elk Point's first business building, a log structure at the southwest corner of Main and Douglas Streets that served as a hotel, trading post, and post office on the Military Road. In 1865, he donated one block of property for the Union County courthouse and one block for the Elk Point Public School. He served on the first city council and in the territorial legislature, was Register of Deeds and county Commissioner, became Elk Point's first postmaster, served in Company B, First Dakota Cavalry, and died in 1908; he is buried in Elk Point Cemetery.