Interior doors

I got to thinking this morning about interior doors. I live in a historic house, built in 1885, and there are doors between every room, or at least there used to be. Some were long gone by the time that I bought the place. The doors between the major rooms on the entry level were glass-paned French doors similar to the picture above(two still remain). It appears that it was once possible to close off every room in the house - the dining room from the kitchen or from the living room and the living room from the parlor and the parlor from the front stairway. The door between the dining room and kitchen was apparently one of those that could swing either way. It's a shame that all that remains of that door is one of the hinges.

So I wondered, when and why did interior doors like that go away as a design feature of houses? I posted that question on the Yahoo Questions site and had an answer back within minutes. The responder opined that interior doors went away when central heating and air conditioning came into vogue, which he/she placed as sometime in the 1940's or 1950's. I guess I can buy that argument, but I'm not sure how prevalent central air was back then. Central heat had been around for some time, albeit mostly boilers and radiators and not forced air. When forced air heating came about I've been told that fireplaces went out of vogue for a while and I've seen this to be the case in a few local historic houses. apparently not having a fireplace indicated the owners wealth by showing that he didn't need a fireplace to heat the house.

The Yahoo answer about interior doors, while it made some sense didn't leave me feeling like I had a valid answer to the time part of the question, maybe just the why part. It also left me wondering why not just leave the doors open, if air circulation was the big issue? I suppose that putting in doors that wouldn't be used would have been a needless expense and thus was eliminated. There was also a movement larger arched doorways between rooms somewhere back in the 30's and 40's; maybe that contributed to the demise of the interior doors.

So, if any of you readers of this blog have a better explaination and timeline for the demise of interior doors between main floor rooms, let me know and I'll pass it on.