Final answer:
During the founding era, several Northern states, including Pennsylvania, Vermont, Massachusetts, Connecticut, Rhode Island, New York, and New Jersey took steps to abolish slavery, reflecting the growing abolitionist sentiment in the North. The Southern states, in contrast, retained the practice, entrenching it further with the advent of the cotton gin. A nationwide ban on slavery was not achieved until the Thirteenth Amendment in 1865.
Step-by-step explanation:
During the founding era of the United States, the movement towards emancipation and the ideals of the Revolution resulted in several states taking action to abolish slavery. Pennsylvania was one of the first when it passed the Act for the Gradual Abolition of Slavery in 1780. At the same time, Vermont banned slavery within its state constitution in the 1770s. In 1783, Massachusetts freed all enslaved people within the state through judicial decisions. Other states followed suit, with Connecticut and Rhode Island enacting laws for gradual emancipation in the early 1780s, and New York and New Jersey adopting similar policies though later in the late 1790s.
The northern states largely led the way in abolition efforts, often driven by sentiments that slavery was in conflict with Christian teachings, the ideals of the Declaration of Independence, and a fear for public safety. Such legislation was generally absent in the South, where slavery remained embedded in agricultural practices and demographic politics like the 'three-fifths compromise'. The invention of the cotton gin further entrenched slavery in the South.
By the early 1800s, the failure to enact national abolition meant that slavery increasingly became a southern institution, leading to significant regional divides that would later culminate in the Civil War. While the North made strides towards emancipation, it was not until the ratification of the Thirteenth Amendment in 1865 that slavery was abolished nationwide.