Numerous airplanes flew daily over the farm where Arnold lived as a small boy, and this likely fueled, at least partly, his early interest in aviation. That he saw so many airplanes in the 1930s was a coincidence of geography and geology. A straight line connecting the present-day Chicago-O’Hare and Minneapolis-Saint Paul airports passes close to Mount Horeb and the dairy farm where Arnold lived. The farm, owned by a family named Donald, also housed an attractive landmark for early pilots with only rudimentary navigation equipment — a Glacier Age limestone remnant the size of a ten-story building that dominated the surrounding terrain.
In 1940, John Steuart Curry, a prominent Midwestern “artist-in-residence” at the University of Wisconsin in Madison, portrayed the massive rock pillar in an oil painting as a favor to a member of the Donald family. The painting hung, unknown by the art community, in the home of a Donald family descendent for more than sixty years. It is now on display at the Chazen Museum of Art in Madison, Wisconsin[i]. You can see a picture of it on page 74 of the pamphlet in this link (warning, big file): http://www.arts.wisc.edu/artsinstitute/pdfs/Arts%20at%20Wisconsin%20history.pdf
The land encircling the present-day “Donald Rock” is a county park, but in the 1930s, the Donald family rented the farm to various tenants, including Arnold’s parents – his father Emil, who had immigrated to the United States from Switzerland in 1919, and his mother Bertha. In 2010, Arnold and his youngest sister, Tere Widstrand, sponsored a bench in the park dedicated to the memory of their parents. You can see Donald Rock as it appears today at this link: http://donaldpark.org/welcome/?page_id=222
[i] Gayle Worland, “Curry Favor,” Wisconsin State Journal (Madison, WI), July 26, 2006.