"Rabbit hole?" I'm older but that's "new" to me! I don't think he ever left Polk County? The 1920 Cooke census might be invalid? He registered for WWI Draft in Polk and had a wife and two children. Find him in 1930 Polk? Better yet, find a Polk County marriage 1910-1920? That might require a "visit" or phone call? Robert Jefferson was in Polk as son of Daniel Jefferson and Alice.