History and Background of the Maps

According to Jefferson M. Moak ("The G. M. Hopkins Company," Mapline, No. 10, June 1978), Griffith M. Hopkins and his brother Henry W. Hopkins founded their own publishing house in Philadelphia in 1865. In the early years, they were involved in county atlas production, but gradually they focused on city plans and atlases. Overall, they produced more than 175 atlases of counties and cities in New England, New York, New Jersey, and Pennsylvania. The company's fortunes declined during the Depression, and it was purchased by the Franklin Survey Company of Philadelphia in 1943.

Hopkins atlases and plat books feature large-scale plates showing lot and block numbers, dimensions, street widths, and names of property owners. These real estate or land ownership maps (also known as plat maps) not only depict property owners, they also show churches, cemeteries, mills, schools, roads, railroads, lakes, ponds, rivers, and streams.

According to our research, the Hopkins company published 49 plat map volumes and atlases of Pittsburgh between 1872 and 1940.

Selection Criteria

The first 26 volumes of map plates we selected were scanned by a vendor and mounted online by the Digital Research Library between 2000 and 2004. The original selection objective for the Historic Pittsburgh collection was to cover as many decades and as much geographic area as possible given our resources at the time. We selected maps that represented an effort to reflect the changing urban landscape of the greater Pittsburgh area from the early 1870s to the late 1930s. Beyond this consideration, priority was given to damaged or deteriorating atlases or plat books that could benefit most from preservation treatment.

In 2008 we decided to digitize the remaining 23 volumes due to continued interest and use of the online maps in order to complete the entire set of Hopkins maps. Plus in the intervening years, the Digital Research Library procured a scanning device capable of digitizing maps of this size. Further, the majority of the needed volumes were held by the Archives Service Center. So in 2009 we commenced scanning the remaining volumes which will become available on this website in the coming months.

Hopkins Real Estate Atlases that were maintained by city departments and bureaus were often systematically updated to reflect extensive housing development, annexation, and street changes within Pittsburgh and the vicinity. Revisions and additions were often ordered from the G. M. Hopkins Co. and pasted onto the original map plates. Newly annexed areas were also noted and stamped by hand in some of the original volumes.

Hopkins Real Estate Atlases have actively been used through the decades, and in many cases, it is rare to find some of these volumes in their original form. The Digital Research Library originally acquired some of these revised volumes for inclusion in the Historic Pittsburgh Maps Collection. When researching family history or history of a house, the researcher should pay special attention to revision dates. We cannot guarantee that the property owners, street names, or city limits presented on some of the online maps were part of the originally published volumes. We have made every effort to note revision dates on the index pages of any volume that has been altered since its publication.

Preservation

To scan the maps, it is necessary to disbind the atlas or plat book (frequently, the original binding is in poor condition). After the volumes are disbound, the condition of each plate is assessed. Treatment procedures include surface cleaning, mending, deacidification, and encapsulation. After scanning, the plates are either rebound using a post-binding structure or stored in an acid-free flat storage box.

Digitization and Online Presentation

The maps in this collection are scanned as 24 bit RGB 300 dpi uncompressed TIFF images. Throughout the course of the project, the maps have been scanned both by vendors (2000-2004) and in-house (2009), using a variety of different scanning technology. Currently, we scan all maps in the University Library Systems' Digital Research Library, using a i2S DigiBook SupraScan A0 scanner.

After the maps are digitized, they are compressed as JPEG2000 files. When a Web user views the maps, a CGI script handles extraction of the appropriate part of the map image from the JPG2 file. A unique feature of JPG2 files is its ability to decompress only that portion of the image requested by the user. Conversion of the extracted component to a .jpg image is done on-the-fly and presented to the end user.

Contact Us with feedback and questions.
Historic Pittsburgh is hosted by the University of Pittsburgh's Digital Research Library.