Image source: Philadelphia and Its Environs, 1875

African American Museum in Philadelphia:  http://www.aampmuseum.org/

American Memory, Library of Congress:  https://memory.loc.gov/ammem/index.html

American Philosophical Society:  https://www.amphilsoc.org/

Athenaeum of Philadelphia:  http://www.philaathenaeum.org/

Emergence of Advertising in America 1850‒1920:      http://library.duke.edu/digitalcollections/eaa/

Encyclopedia of Greater Philadelphia:  http://philadelphiaencyclopedia.org/

Fairmount Water Works:  http://fairmountwaterworks.org/

Free Library of Philadelphia:  http://www.freelibrary.org/

Germantown Historical Society:  http://www.germantownhistory.org/

Grand Army of the Republic Museum and Library:  https://garmuslib.org/

Greater Philadelphia GeoHistory Network:  https://www.philageohistory.org/geohistory/

HathiTrust Digital Library:  https://www.hathitrust.org/

Hidden City Philadelphia:  http://hiddencityphila.org/about-3/

Historical Society of Frankford:  http://thehistoricalsocietyoffrankford.org/

Historical Society of Pennsylvania:  http://hsp.org/collections

Independence National Historical Park:  https://www.nps.gov/inde/index.htm

Independence Seaport Museum: http://www.phillyseaport.org/

Internet Archive:  https://archive.org/index.php

Library Company of Philadelphia:  http://www.librarycompany.org/

Making of America, Cornell University Library:  http://ebooks.library.cornell.edu/m/moa/

Making of America, University of Michigan Library:  http://quod.lib.umich.edu/m/moagrp/

National Railway Historical Society, Philadelphia Chapter:  http://www.trainweb.org/phillynrhs/

Pennsylvania Brewery Historians:  http://pabreweryhistorians.tripod.com/

Philadelphia Architects and Buildings:  https://www.philadelphiabuildings.org/pab/

Philadelphia City Archives:  http://www.phila.gov/phils/carchive.htm

Philadelphia History Museum at the Atwater Kent:  http://www.philadelphiahistory.org/

PhilaPlace:  http://www.philaplace.org/

Philly H₂O:  http://www.phillyh2o.org/index.htm

PhillyHistory.org:  http://www.phillyhistory.org/PhotoArchive/Home.aspx

Places in Time: Historical Documentation of Place in Greater Philadelphia:                            http://www.brynmawr.edu/iconog/frdr.html

Preservation Alliance of Greater Philadelphia:  http://www.preservationalliance.com/

 Society for Industrial Archaeology, Oliver Evans Chapter:      http://www.workshopoftheworld.com/introduction/oe.html

Society of Architectural Historians (SAH), Philadelphia Chapter:  https://philachaptersah.org/

Urban Archives, Temple University:  https://library.temple.edu/scrc/urban-archives