On this day in 1775, Philadelphia Quakers formed the first abolitionist organization in the U.S., the "Society for the Relief of Free Negroes Unlawfully Held in Bondage". Although they won reforms, they never succeeded in abolishing slavery.

Although there are records of Quakers condemning the "traffic of Men-body" as early 1688, this group (predominantly but not exclusively Quaker) was the first official organization to work for the abolition of slavery.

The organization was re-formed in 1784, renamed the "Pennsylvania Abolition Society" (PAS). This version of the group began to grow more influential, broadening its membership to prominent figures as Benjamin Franklin and Benjamin Rush, who both helped write the Society's new constitution.

In 1787, the PAS unsuccessfully petitioned the Constitutional Convention to institute a ban on slavery. The following year, they successfully lobbied the Pennsylvania legislature to amend the gradual abolition act of 1780, winning reforms like the banning of transporting enslaved children and pregnant women out of Pennsylvania and the sending of slave ships from the city.

The amended act also imposed heavier fines for kidnapping the enslaved, and made it illegal to separate enslaved families by more than ten miles.

The group's influence waned in the decades leading up the Civil War amid economic crises and an increasing anti-black sentiment in the region. Despite their efforts at gradual abolition, chattel slavery was not abolished in the United States until 1865.