The connection between abortion, slavery, and the decline of private property is not accidental. Life, liberty, and property are, after all, the great triad of natural rights named in the Virginia Declaration of Rights in 1776. Jefferson omitted property from the Declaration of Independence a month later probably because of “discomfort” over slavery. It was, after all, a bit tricky to be demanding full rights for free men and, at the same time, denying any rights at all to half a million others.
The anti-slavery movement, however, gained a great deal of momentum in the northern states and the bordering southern states following the Revolution. By 1810, nearly all slaves north of Mason-Dixon were free, while approximately 13.5% of the black population just south of the line were free. Of the northern states, only Delaware still had slavery (cir. 1,800 people) by the Civil War.
The problem, however, was the invention of the cotton gin. Ordinarily, the effect of advancing technology is to displace human labor from the production process. That is, in fact, what the cotton gin did. Cotton can’t be carded like wool; those seeds had to be picked out by hand. Before the cotton gin, it could take a full day for an industrious slave to pick the seeds out of a pound of cotton — and a pound of cotton didn’t go for much.
That limited the ability to grow enough cotton to be profitable. Slaves were expensive, and the market price of cotton, especially in competition with linen and wool, was too low to justify the cost in many cases. Consequently, expensive slaves were mostly employed in manufacturing in competition with cheap free labor, or in growing, e.g., indigo or tobacco. As the former had substitutes, and the latter had a great deal of competition from free labor, the demand for slaves was decreasing.
It was, frankly, becoming just plain uneconomic to spend up to $3,000 for a prime field hand. To the acquisition cost you had to add the cost of maintenance and, in some cases, wages. Yes, wages. A number of highly skilled slaves, especially in manufacturing, were paid, and some even purchased their freedom and went into business for themselves . . . and some of them bought their own slaves.
Free labor, on the other hand, could be hired for $150 a year if that much, and you didn’t have to feed, clothe, or house them or their families, or take care of them in their old age. In the 1840s, John Mitchel of the Young Ireland movement claimed that American black slaves were better treated than the Irish peasantry and some northern factory workers. (Which, of course, begs the question as to whether being under the absolute control of another human being enters into the determination of what constitutes “good treatment.”)