<P> New Orleans became nationally important as a slave market and port, as slaves were shipped from there upriver by steamboat to plantations on the Mississippi River; it also sold slaves who had been shipped downriver from markets such as Louisville . By 1840, it had the largest slave market in North America . It became the wealthiest and the fourth - largest city in the nation, based chiefly on the slave trade and associated businesses . The trading season was from September to May, after the harvest . </P> <P> Slave traders were men of low reputation, even in the South . In the 1828 presidential election, candidate Andrew Jackson was strongly criticized by opponents as a slave trader who transacted in slaves in defiance of modern standards or morality . </P> <P> The treatment of slaves in the United States varied widely depending on conditions, times and places . The power relationships of slavery corrupted many whites who had authority over slaves, with children showing their own cruelty . Masters and overseers resorted to physical punishments to impose their wills . Slaves were punished by whipping, shackling, hanging, beating, burning, mutilation, branding and imprisonment . Punishment was most often meted out in response to disobedience or perceived infractions, but sometimes abuse was carried out to re-assert the dominance of the master or overseer of the slave . Treatment was usually harsher on large plantations, which were often managed by overseers and owned by absentee slaveholders, conditions permitting abuses . </P> <P> William Wells Brown, who escaped to freedom, reported that on one plantation, slave men were required to pick 80 pounds per day of cotton, while women were required to pick 70 pounds; if any slave failed in his or her quota, they were subject to whip lashes for each pound they were short . The whipping post stood next to the cotton scales . A New York man who attended a slave auction in the mid-19th century reported that at least three - quarters of the male slaves he saw at sale had scars on their backs from whipping . By contrast, small slave - owning families had closer relationships between the owners and slaves; this sometimes resulted in a more humane environment but was not a given . </P>

Which of the following ended slavery in the united states