Since May I have been doing some in-depth research into the development =
of a specialized urban industrial community: the leather tanners of =
Pittsburgh. Because I am doing this independent of the usual budgetary, =
spatial and time constraints of CRM projects, I have encountered some =
interesting and disturbing trends in the accuracy of the usual research =
tools used to develop research designs for historical archaeological =
surveys.
 
Like everyone else out there in CRM-Land, I have relied on historical =
maps, city directories, census data, the existing landscape and =
historical documents as the bases for developing field strategies to =
identify historical archaeological resources.  After spending five =
months plodding through deeds, census data, maps (city atlases and =
original plats), published histories, informant interviews, etc. I have =
found that if I relied solely on the tools available to me during CRM =
projects that more than 65% of the industrial sites clustered in two =
parts of the former Allegheny City (now Pittsburgh's North Side) would =
not have been identified.  A cursory pedestrian survey of the two areas =
appears to indicate extensive urban development and redevelopment, a =
finding that would be supported by existing cartographic resources =
available to CRM researchers (Hopkins atlases published in 1872, 1882, =
1891, 1906, etc. and a series of Sanborn maps published after 1893).
 
What the maps fail to show are the literally dozens of emergent =
industrial sites associated with meat processing and leather tanning.  =
Published histories of the vicinity (Allegheny City) and of Pittsburgh =
failed grasp the extensive nature of the local hide and leather =
industries.  Even a 1985 survey of National Register sites in Pittsburgh =
by a competent archaeologist relied on very, very inaccurate secondary =
historical information and failed to identify both the industrial =
district and its individual sites.=20
 
The cartographic data are flawed in two significant areas. First, there =
is a substantial amount of "map gap" (the interval between surviving =
historical maps).  The earliest detailed surviving published maps were =
produced in the 1850s. From ca. 1855 until 1872 there are no detailed =
maps of this vicinity.  During this interval the number of tanneries in =
Allegheny City peaked and began another cycle of growth which then was =
tempered after the 1873 depression.  Within the interval from ca. 1855 =
until 1872, a number of significant tanneries were founded, successfully =
operated and closed for one reason or another.  In fact, the period of =
greatest development occurred between 1857 and 1865.
 
The second big flaw in the cartographic data is the failure to identify =
individual properties as tanneries. By the time the first property atlas =
was published in 1872 many of the tanners had been able to amass =
considerable amounts of capital. Long before the first maps were =
published, the tanners owned several tracts within a relatively confined =
area.  And, because of the kinship dynamics of very strong craft =
dynasties, a few families also owned multiple tanneries within a close =
proximity of one another.  Also related to the problem of site =
identification through documentary or cartographic data is the fact that =
for the most part only property owners are shown in the maps.  My =
research has identified many tanners operating tanneries on property =
owned by their wives fathers or on tracts managed by a wealthy =
landholding partnership.
 
Anyway, back to the point. While doing this research I started to =
reflect on some of the many large-scale projects I have worked on where =
teams of historical researchers and archaeologists have collaborated to =
identify potential historical archaeological resources based on =
documentary and cartographic data. I have "written-off" areas because of =
what appeared surficially - and even after some testing - to be =
"disturbed" or on the basis of research did not appear to have any =
potential to yield NRHP significant sites.  I am wondering now just how =
many and of what type of sites have I overlooked because of similar =
situations. After all, at face value, it looks like there's a tremendous =
amount of cartographic and documentary data covering this part of =
Pittsburgh. Yet, beneath the veneer there are some very disturbing =
lessons to be learned about the reliability of "abundant" and detailed =
historical documents.
 
Any thoughts?
 
David S. Rotenstein