The society library houses books, newspapers, microfilm, periodicals and some 20 million manuscripts. They are one of the nation’s largest non-governmental repositories of documentary materials. Within their collections are church registers, censuses, vital records, taxes and genealogical files.
Several major additions to the HSP increased its collections to become nothing short of amazing. In 2002 the records of the Balch Institute for Ethnic Studies and in 2006 the records of the Genealogical Society of Pennsylvania merged into the HSP. This enhanced the HSP to become a major repository of ethnic and immigration studies. Part of the Balch Institute collections were the records of the Scotch Irish Foundation to which the HSP has a special 16 page finding aid describing and inventorying: http://hsp.org/sites/default/files/legacy_files/migrated/findingaid3093scotchirish.pdfThis particular archive of records includes 37 boxes, 11 volumes from 1889 through 2001, with the majority dating from 1940 through 1995. They include membership files, family registrations and genealogies. Another collection is many transfer certificates from the Loyal Orange Institution of the United States of America 1883-1974. There is also a finding aid to this archive of records: www2.hsp.org/collections/Balch%20manuscript_guide/html/loi.html
The HSP publishes the respected journal, Pennsylvania Magazine of History and Biography. This magazine has been published since 1877. The HSP should not be neglected, especially for Pennsylvania, Delaware and northern New Jersey research. However, their collections reach far beyond this core area.