While doing a little demo on a house my sister & I own in northwest AR, I noticed that all interior walls are 1x2 clear pine tongue & groove horizontal strips (no knots) nailed to rough sawn oak 2x4's on 16 inch centers. Some of the interior walls were also covered by by a fabric type wallpaper nailed to the 1x2's. I believe the rafters are 2x6's. My dad said our uncle didn't get electric until some time in the 1950's and what wiring I saw was knob & tube. I'm guessing the house was built in the 1930's. What is really amazing is that all walls are square and none of the floors squeak. Sorry, no pics.