When Did Pennsylvania Abolish Slavery? 1780 Act to Prigg Ruling

Pennsylvania abolished slavery in stages beginning on March 1, 1780, when the state legislature passed the Act for the Gradual Abolition of Slavery, the first law of its kind in the United States. The word “gradual” carried the weight: the act freed no one who was already enslaved. It set up a decades-long process under which slavery would slowly disappear. The last enslaved people in Pennsylvania still appear in the 1840 federal census, and by 1850 none were recorded, meaning the institution took roughly seventy years to fully end in the state.¹

What the 1780 Act Actually Did

The Act for the Gradual Abolition of Slavery passed the Pennsylvania Assembly on March 1, 1780, by a vote of 34 to 21. George Bryan, then vice president of the state’s Supreme Executive Council, guided the bill through the legislature. John Bayard signed as Speaker of the Assembly and Thomas Paine as Clerk of the General Assembly.²

The preamble is sweeping. It ties abolition directly to the Revolution, arguing that having been “tyrannically doomed” to “thraldom” by Britain, Pennsylvanians had a duty “to extend a portion of that freedom to others, which hath been extended to us,” and declaring that differences in complexion were irrelevant because “all are the work of an Almighty Hand.”³

The operative sections were far more cautious. No one already enslaved on March 1, 1780, was freed; those people remained enslaved for life unless their owners chose to release them. Children born to enslaved mothers after that date were nominally free, but they were required to serve their mother’s owner as indentured servants until age 28.²³⁴ Earlier colonial statutes from 1705, 1725, 1761, and 1773 governing the trial, regulation, and taxation of enslaved people were repealed.

So 1780 is the right answer to “when did Pennsylvania abolish slavery” only in the sense that it is when abolition began as a legal process. The institution itself kept running.

Why It Took Seventy Years to End

Because the act emancipated no living enslaved person and bound the next generation until age 28, the slave population declined slowly and unevenly. The federal census tells the story:

1790: 3,707 enslaved people
1800: 1,706
1810: 795
1820: 211
1830: 403 (a temporary uptick likely reflecting classification disputes)
1840: 64
1850: 0¹

Those numbers represent people born before 1780 whose status the act never touched, plus the children born after the act who were still working off their 28-year indentures. The Pennsylvania Abolition Society, founded in 1775 as the Society for the Relief of Free Negroes Unlawfully Held in Bondage and later presided over by Benjamin Franklin, employed lawyers throughout this period to bring freedom suits, pursue kidnappers, and challenge illegal cross-border sales, freeing thousands of people through litigation.⁵⁶

Closing the Loopholes: The 1788 Amendments

The original law had serious gaps, and slaveholders exploited them. Some simply failed to register their enslaved property. In 1781, conservative legislators tried to extend the registration deadline and re-enslave people whose owners had missed it, and they even attempted an outright repeal. Both efforts failed.¹

Slaveholders in counties bordering Maryland and Delaware kept buying and selling across state lines in open violation of the act. On March 29, 1788, the legislature responded with a substantial amendment package. It prohibited removing enslaved people from the state to circumvent emancipation, banned outfitting ships in Pennsylvania ports for the slave trade under a £1,000 penalty, and forbade separating husbands from wives or parents from children under four by more than ten miles without consent. Owners who transported pregnant enslaved women out of state to prevent their children from being born free faced a £75 fine. Kidnapping a Black person out of the state for sale into slavery carried a £100 fine and six to twelve months of hard labor.⁷

How the Courts Read the Law

The first major judicial test of the 1780 act came in Respublica v. Negro Betsey, decided by the Pennsylvania Supreme Court in 1789. Samuel Moore held three people, Betsey, Cate, and Isaac, who had all been born before the act’s passage. Moore had failed to register them by the November 1, 1780, deadline, and he argued they should still be treated as servants until age 28. The court disagreed. Justices Atlee and Rush held that unregistered individuals were free, and that the 28-year servitude applied only to children born after March 1, 1780, to properly registered mothers. Justice Bryan, who initially leaned the other way, changed his vote, saying he would not “press an argument against liberty.”⁸ The decision established that registration was a strict precondition for any claim on an enslaved person, and that ambiguities in the statute would be resolved in favor of freedom.⁹

Later Flashpoints: Fugitive Slaves and Prigg v. Pennsylvania

Pennsylvania’s borders with slave states kept the question of abolition active in the courts long after the state’s own enslaved population had shrunk. The federal Fugitive Slave Act of 1793 let slaveholders pursue people who had escaped to free states, and Philadelphia’s growing free Black community became a frequent target of slave catchers and outright kidnappers.

Pennsylvania answered with personal liberty laws. An 1820 statute barred state marshals, justices of the peace, and jailers from assisting in the recovery of fugitives. The 1826 law went further, making it an offense to forcibly remove a Black person from the state for the purpose of enslavement and requiring enslavers to produce evidence beyond their own testimony, with at least two witnesses, to prove an alleged fugitive’s identity.¹⁰

That 1826 law reached the U.S. Supreme Court in Prigg v. Pennsylvania. In 1837, Edward Prigg, a Maryland slave catcher, seized Margaret Morgan and her children from their home in York County and carried them to Maryland. A Pennsylvania grand jury indicted Prigg for kidnapping under the 1826 law, and he was convicted in 1839.¹¹ On March 1, 1842, Justice Joseph Story, writing for the majority, struck down Pennsylvania’s law as unconstitutional, holding that the Constitution’s Fugitive Slave Clause gave slaveholders an “absolute positive right” to recapture fugitives and that federal power over the subject was exclusive.¹² Story’s opinion carried an important limitation, however: Congress could compel only federal officers to enforce the fugitive slave laws, not state officers. States could legally refuse to cooperate.¹³

Pennsylvania took that opening. In 1847, the state enacted a non-cooperation law forbidding state officers from assisting in the rendition of fugitive slaves and barring the use of state prisons to hold suspected fugitives.¹⁰ Southern legislators called non-cooperation laws like this a primary reason the 1793 Fugitive Slave Act had become, in the words of Virginia Senator James Mason, “a dead letter,” and that frustration fueled the far more aggressive Fugitive Slave Act of 1850.¹⁴

Where Pennsylvania Stood Among the Northern States

Pennsylvania’s 1780 statute was the first legislative abolition of slavery in the United States, but other northern states reached the same end by different routes. Vermont’s 1777 constitution banned adult slavery but left loopholes for children that persisted for decades. Massachusetts courts effectively ended slavery through judicial rulings in 1783, interpreting the 1780 state constitution as incompatible with the institution. New York passed its own gradual emancipation act in 1799, with children born to enslaved mothers freed after 25 to 27 years, and officially abolished slavery in 1827. New Jersey started latest, in 1804, and moved slowest: enslaved “apprentices for life” still appeared in the 1860 census, and the state did not formally outlaw slavery until the Thirteenth Amendment in 1865.¹⁵

Across all these states, emancipation was structured to minimize the economic disruption to slaveholders, extracting years of additional unpaid or barely compensated labor from the people who were supposed to be gaining their freedom. Pennsylvania set that template. The legislature declared slavery wrong in 1780, and the law carried out that declaration in a way that let the institution survive on Pennsylvania soil until roughly 1850.

1
Pennsylvania Historical and Museum Commission. Abolition of Slavery
2
National Park Service. Pennsylvania Gradual Abolition Act of 1780
3
Yale Law School, Avalon Project. Act for the Gradual Abolition of Slavery
4
Library Company of Philadelphia. Black Founders: Section 4
5
National Archives. Benjamin Franklin and the Pennsylvania Abolition Society
6
American Revolution Museum. African American Freedom and Community, 1780-1813
7
Encyclopedia Virginia. An Act to Explain and Amend an Act for the Gradual Abolition of Slavery
8
Justia. Respublica v. Negro Betsey, 1 U.S. 469
9
Pennsylvania Supreme Court. Landmark Decisions
10
Dickinson College, House Divided Project. State Laws and Freedom Seeking
11
Maryland State Archives. Margaret Morgan Biography
12
Justia. Prigg v. Pennsylvania, 41 U.S. 539
13
National Constitution Center. On This Day: Prigg v. Pennsylvania
14
Cambridge University Press. Captive’s Quest for Freedom: Fugitive Slave Law
15
People Not Property, Historic Hudson Valley. Gradual Emancipation Acts