Personal Materials series contains primarily correspondence and personal materials of the John R. Winterbotham III family. This includes many letters and notes written while Chloe T. F. Winterbotham was employed at Mathieson Alkali Works during World War II, European travel diaries of J. H. and John R. Winterbotham, and correspondence pertaining between Chloe T. Winterbotham and French family members concerning a dispute over an inheritance.

The Financial Documents series contains estate and trust materials, as well as papers pertaining to properties owned by the Winterbothams in Chicago and the Midwest, including a pig farm in Elkhart, Nebraska and a ranch in Eldred, Illinois. Also includes papers pertaining to a co-op building at 1301 N. Astor Street, Chicago that was apparently built by the Winterbotham family