Slavery’s Threat to Working Free Men
There is simply no comparing free with paid labor when it comes to labor expenditures. Because of this, the earnings of working-class men in the Southern states were drastically reduced. Slaves were primarily employed in agriculture, but even free laborers in industrial jobs like construction lost their ability to collectively bargain because state governments required slave owners to donate their slaves' labor for public works, which led to the permanent employment of hundreds of thousands of slaves in those positions. As a result, by 1860, the average annual wage for free laborers in the South was $103, compared to $141 for workers in the North.
The class who owned slaves benefited secondarily from this. Many white laborers were forced to participate in the slave trade themselves because the majority of industries did not provide living wages. In order to keep Black slaves in line, overseers and slave-catchers created more racial hatred, which boosted popular support for slavery.