For Washington County, you can find Sanborn Maps here
For Westoreland County, you can find Sanborn Maps here
For Fayette County, you can find Sanborn Maps here
And lastly Greene County is here
My suspicion is you'll have to download the maps of interest, georeference them and write out a world file for the jpg or tif. But it should work. Now the key is do these links have the coverage you require?