There are many city directories online here at ancestry. See if they appear in any of them. If they do, then you know they were alive at that time.

You can't really estimate any type of death date based on what you have right now. Even though the average life span was shorter, if you take out the infant mortality, the life span once they actually reached adulthood was often quite long.

Since he lived past 1940, try ordering the death certificate, specifying what you do know. Check the particular state's website for the procedure. Most will do a reasonable search for a small fee when you don't know the actual death date. Don't use Vital Check.as they will ask for data you don't have yet.