The Decline of Northern Slavery and the Rise of the Cotton Kingdom

Learning Objectives

  • Examine the critical role slavery played in the early Southern economy

The market revolution economy depended upon both free-market labor factories in the North and slave-labor plantations in the South. By 1832, textile companies made up more than 80% of American corporations valued at over $100,000. These textile mills, worked by free-market laborers, depended upon southern cotton and the vast new market economy spurred the expansion of Southern plantation operations, including an increase in the number of enslaved people being sold to cotton-producing plantations.


By the early nineteenth century, states north of the Mason-Dixon Line had taken steps to abolish slavery. Vermont included abolition as a provision of its 1777 state constitution. In 1804 New Jersey became the last of the northern states to adopt gradual emancipation plans. There was no immediate moment of jubilee for northern enslaved persons, however, as many states only promised to liberate future children born to enslaved mothers. Such laws also stipulated that children remain in indentured servitude to their mother’s master in order to compensate the enslaver’s loss. James Mars, a young man indentured under this system in Connecticut, risked being thrown in jail when he protested the arrangement that kept him bound to his mother’s master until age twenty-five. Pennsylvania’s Emancipation Act of 1780 stipulated that freed children serve an indenture term of twenty-eight years. Gradual emancipation still defended the interests of Northern slave-holders and kept another generation of Black Americans under the control of White citizens.


Quicker routes to freedom included escape or direct emancipation by masters. But escape was dangerous and the voluntary liberation of enslaved persons by slave-holders, known as manumission, was rare. Congress, for instance, made the harboring of a fugitive enslaved person a federal crime by 1793. Hopes for manumission were even slimmer, as few Northern enslavers emancipated their own enslaved workers. For example, roughly one-fifth of the White families in New York City owned enslaved persons and yet fewer than 80 enslavers in the city voluntarily manumitted enslaved workers between 1783 and 1800. By 1830, census data suggests that at least 3,500 people were still enslaved in the North. Elderly Connecticut enslaved people remained in bondage as late as 1848 and in New Jersey until after the Civil War.

Emancipation proceeded slowly, but proceeded nonetheless. A free Black population of fewer than 10,000 at the time of the Revolution increased to 200,000 by 1810. Growing communities of free Black Americans fought for their civil rights. In a number of New England cities, free Black Americans could vote and send their children to public schools. Most northern states granted Black citizens property rights and trial by jury. Black Americans in the North also owned land and businesses, founded mutual aid societies, established churches, promoted education, developed print culture, and voted.

The Cotton Boom

Nationally, however, the enslaved population continued to grow to a total of 700,000 in the early years of the nineteenth century. The growth of abolitionism in the North and the acceleration of slavery in the South created deep divisions between the two regions. Slavery declined in the North but became more deeply entrenched in the South, owing in part to the development of a profitable new staple crop: cotton. Eli Whitney’s cotton gin, a simple hand-cranked device designed to mechanically remove sticky green seeds from raw cotton, allowed southern planters to dramatically expand cotton production for the national and international markets. Technological innovations elsewhere—water-powered textile factories in England and the American northeast, which could rapidly turn raw cotton into cloth—increased demand for southern cotton and encouraged White Southerners to expand cultivation farther west, to the Mississippi River and beyond. Slavery’s profitability had lagged in the tobacco economy, but cotton gave it new life. Eager cotton planters invested their new profits in more slaves.

The cotton boom fueled speculation in slavery. Many slave owners leveraged potential profits into loans used to purchase ever-increasing numbers of slaves. For example, one 1840 Louisiana Courier ad warned “it is very difficult now to find persons willing to buy slaves from Mississippi or Alabama on account of the fears entertained that such property may be already mortgaged to the banks of the above named states.”

Lowell, Massachusetts

Figure 1. Sidney & Neff, Detail from “Plan of the City of Lowell, Massachusetts,” 1850.

New national and international markets fueled the plantation boom. American cotton exports rose from 150,000 bales in 1815 to 4,541,000 bales in 1859. The Census Bureau’s 1860 Census of Manufactures stated that “the manufacture of cotton constitutes the most striking feature of the industrial history of the last fifty years.” Enslavers shipped their cotton to textile manufacturers in the North as well as overseas. Northern insurance brokers, merchants, and exporters profited greatly from this new market trend.

While the United States ended its legal participation in the global slave trade in 1808, slave traders moved 1,000,000 enslaved laborers from the tobacco-producing Upper South to cotton fields in the Lower South between 1790 and 1860, generating upwards of $12,000,000 annually. This harrowing trade in human flesh supported middle-class occupations such as bankers, doctors, lawyers, insurance brokers, and shipping agents, and it facilitated the expansion of northeastern textile mills.

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manumission: the process of a slave-owner voluntarily freeing a slave. From the Latin words “manus” (hand) and “mittō” (to send).

Mason-Dixon line: a state border between Pennsylvania and Maryland, which became the unofficial line of demarcation between free states and slave states.