However belated it may be, I'd like to add that this is a very superb find indeed! While the date is unambiguously pre-WW2 by a very large margin, it's reasonable to expect that many of these chests from the interwar period and perhaps even earlier would have still been in use early in the war, especially with National Guard and Organized Reserve units. The latter in particular were always chronically short of equipment and personnel, and even the Guard historically seldom received the most up-to-date equipment. Units in both components made do with whatever happened to be at hand, and usually did so magnificently.
I remember an example from my own experience as a young soldier in the National Guard (1981 -- Ronald Reagan had just taken office and I was still finishing high school in civvy life): I was a radio operator with the Communications Platoon of a Long Range Reconnaissance company, and one of the skills we were required to maintain was good old-fashioned Morse Code. We could not get a decent set-up of training apparatus for everyone through the normal military supply system, but it so happened that within our very own armory we had a well stocked unit museum filled with artifacts dating to both World Wars and even earlier. One of the guys who happened to be quite deft with the repair of archaic electronics pulled a pre-WW1 multi-station Morse Code training oscillator, capable of accommodation sending and receiving practice for six men at a time, from the museum, put it back into original working order, and that was what we used for the next several years. Again, this happened in the early 1980s, yet the training device itself dated all the way back to 1909!
My main point? Yes, it seems very plausible indeed that some of these chest would have still been in use, especially in the ZI, and especially in the 1939-41 period. Given the 70-something year span shown in my personal example above, it's no stretch to extrapolate that some unit somewhere in the US Army could very well have had a few bits and pieces of kit dating back even to the Spanish-American War, perhaps even the Indian Wars era. If one were doing a representation of the Louisiana Maneuvers re-enacted, my thought is that including a few pre-war items would actually lend to the authenticity.