A note about the 'PGH' abbreviation commonly seen used to mean 'Pittsburgh'. This is found in both historical and modern records for Pittsburgh, and is also recognized by the Supreme Court of the state of Pennsylvania. This page is a lookup site for city abbreviations and may contain a note about this: http://www.city-data.com/forum/general-u-s/255793-does-your-city-have-abbreviation-4.html
A wiki article describing an online collections is found at:
Timeline for Pittsburgh and other resources at "Historic Pittsburgh" website http://digital.library.pitt.edu/pittsburgh/
- U.S. Census Schedules - University of Pittsburgh, for years 1850, 1860, 1870, 1880
DonsList City Directories with images. Search here for Directories, Cemeteries, Censuses and more.
Pittsburg Dispatch (1889-1892) on Chronicling America: Historic American Newspapers