----------------------------Original message---------------------------- Amen, brother! Of course, any measurement reduced as much as a Sanborn is will be inaccurate, e.g. not as correct as the architects blueprint. Our experience here at NYPL, with architectural, archaeological, urban studies, and other student types, has been very positive over the years vis a vis Sanborn. It is not at all surprising to me that information relating to the interior of a closed block might not be updated accurately, consistently, every year. One wonders how many linear feet of building and lot measures there are in total for the Manhattan cartographer to keep track of, hmmm?