<P> Those enslaved in Pennsylvania before its 1780 Act became law continued to be lifelong slaves, unless manumitted . Also, the 1780 Act and its 1788 Amendment did not apply to fugitive slaves from other states or their children . Pennsylvania tried to extend rights to fugitive slaves through an 1826 personal liberty law, but it and the 1788 Amendment were ruled unconstitutional by the US Supreme Court in Prigg v. Pennsylvania (1842). </P> <P> Although slavery steadily declined in Pennsylvania, the state that had initially led the way toward abolition tolerated it for decades after it ended in New England . The 1840 U.S. Census listed 47,854 (99.87%) of the state's blacks as free, and 64 (0.13%) as slaves . Legal slavery ended in Pennsylvania in 1847, when the several dozen remaining slaves (the youngest was 67) were freed . </P> <Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (August 2012) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (August 2012) (Learn how and when to remove this template message) </Td> </Tr>

Who wrote an act for the gradual abolition of slavery