New to hunting down info

Hit the library (and google history tid-bits on your area). To look for 1) stage stops locations (that are hopefully not built over now, 2) old resorts and campgrounds (hopefully totally defunct by the 1950s), 3) old country picnic sites, etc.....

As for inner-city places (to tell age), you can sometimes get a sense on the age of parts-of-town by a) old topographic maps (if they're available for your area) b) realtor.com and zillow have options to see the date homes were built. So you can assume that parks, schools, sidewalk tearouts, etc... immediately nearby probably date to the same era.