All Philadelphia addresses are approximated from listings in 19th-century city directories before the city’s consolidation in 1854. In 1854 surrounding areas were added to the Philadelphia city proper, which altered the street numbering. The locations are inferred from an 1854 conversion chart based on street blocks and not exact addresses. Few markers represent an exact building. An address may also be inaccurately attributed to a contributor if a directory listing was for another individual with the same name. Addresses outside Philadelphia are not exact and localized only by city.