The Riverdale Ranch, about 8 miles northeast of Cascade on the north side of the Missouri River, was owned by Henry H. Nelson. An island in the river is named Nelson Island, and there was a community known as Riverdale.

Henry H. Nelson was born in Veile Ampt, Denmark, in January 1860. In 1866 the family emigrated to Quebec and then moved on to Hutchinson, Minnesota. He grew up on the family farm beginning at age 15 taught a rural school in the winter. He drove a herd of horses to Deer Lodge, Montana, in 1881 and decided to stay. He worked briefly in the Sun River area and then in 1887 proved up on a homestead along the Missouri River, northeast of Cascade. He married Anna Putnam in 1892. Over the years up to 1902, he added more land to his ranch. After 1903 Nelson became a railroad and irrigation canal builder in the Glasgow area. He died at Vandalia on October 15, 1914.

Thomas Dean was born in England in January 1865. He came to the United States in 1895, and went to work for the Riverdale Ranch as a bookkeeper.