One family, the DeWolfs, out of Rhode Island were one of the leading families in the slave trade. From the year 1769 to just before the civil war, more than 10,000 free Africans were brought into the country on DeWolf ships. The importation of slaves was outlawed in 1808, but the DeWolf family was so powerful that they had influence with the president and were able to continue their business. The DeWolfs developed a triangle route of trading that involved Rhode Island, Cuba, and the African coast. They were trading rum and slaves and reaping a massive profit. This family of northerners were clearly not against slavery, they were supporting its continuation by illegally bringing more slaves into America, and continuing to sell them. This economic dependence on slavery by northerners led to many northerners resisting abolitionist movements.
This chart shows how the economy of Lowell was dependent on slave labor. The textile factories were completely dependent on the cotton that was harvested by slaves. The slave population can be seen to clearly coincide with a dramatic increase in jobs in the Lowell mills, and an increase in cloth production in Lowell. This means that the more slaves that were brought into the united states resulted in a greater profit for the owners of the mills and more jobs for the lower class workers. This means that the jobs of the workers depended on the slavery of millions of blacks.
This broadside from a Public Meeting in Lowell is strongly advocating against slavery. The persons at this meeting claimed that they are against abolition because they believe that it is an "infraction of their [southerners] rights". The glaring irony in this statement is ridiculous. The people of Lowell are so concerned for the rights of the southerners, but what about the rights of the millions of blacks who are enslaved? The first signer of this broadside is none other than Kirk Boot, an owner of a mill in Lowell.
Although some citizens of the north were against slavery on moral grounds, much of the population depended on slavery for their welfare and therefore supported slavery. The perception of a "morally superior" north is definitely not true.