When the Declaration of Independence was drafted in 1776 the founding fathers failed to establish slavery. Some of them were slave owners.
The northern states took after the war of independence many measures against slavery. For example Vermont banned it in 1777 and Massachusetts in 1783.
In the southern states, on the contrary, accelerated progress was made in the institutionalization and expansion of slavery.
The Congress passed in 1793 a law against slaves fleeing their masters. In 1808 the slave trade was banned and in 1809 the participation in it of Americans was forbidden; but slavery was not forbidden.
When the aboriginal territories and those previously colonized by Spain and France were annexed to the national territory, (annexation of Kentucky, 1792, Tennessee, 1796, Ohio, 1803, French Louisiana, 1803, which includes Alabama, Arkansas, Mississippi, etc., Florida, 1819) slave activity was consolidated in the new southern states of the Union. In 1820 the Masson-Nixon line was drawn, establishing the separation between slave states to the south and non-slave states to the north.
The combination of the prohibition of trafficking but the non-prohibition of the practice of slavery brought with it the smuggling of slaves and with it a large increase in the price of slaves. This influenced in a better treatment and care on the part of the masters to its slaves.
In general there were two types of slaves, those of household service and plantation workers. The latter had to perform approximately 16 hours of daily work, lived in not very well-built huts and ate. The food was monotonous: salted pork, a bushel of cornmeal and molasses, sometimes vegetables and, when they bought or stolen, a chicken.