Slavery was integral to the United States' transformation from a nascent conglomerate of colonies to a global economic powerhouse over the course of less than a century. In the mid-19th century, nearly 60 percent of the country's exports consisted of cotton produced through slave labor.
But a new set of maps from Radical Cartography shows just how much slavery exploded in the US, due in large part to the invention of Eli Whitney's cotton gin, which sparked the beginnings of the Industrial Revolution.
Following the Revolutionary War, the newly liberated Americans had to grapple with celebrating their newfound independence as an entire group of people remained in chains. The profitability of cotton, a labor intensive crop, was also in question.
However, in 1793, the cotton gin revolutionized the cotton industry. The cleaning and spinning processes were now mechanized and more efficient than ever. Slavery was now here to stay, exploding in the decades that followed, and provided enough enough raw material to support the North's textile mills.
This is the reason behind the rise and fall of slavery on both sides of the Mason Dixon line in the maps: When the South found a way to produce more and more cotton, the North was freed from needing their own class of slaves to provide the raw material for their textile industry.
The slave population in the South stayed at a steady 34 percent as the US expanded west. But in 1840, that meant there were almost 2.5 million enslaved people compared to 654,121 in 1790, peaking to almost 4 million in 1860. During the same period, slavery largely disappeared in the North.