Tag Archives: slave population

Statistics of Slaves

I vowed to spend May documenting all the curriculum I’ve built that’s kept me from writing much. But writing up lesson always takes forever, so I don’t know how much I’ll get done.

I’ve revamped a lot of my history course since I first taught it in the fall of 2014,  but this lesson has remained largely unchanged. I was looking for data, originally for a lecture, on the growth of slavery after Eli Whitney went south for a visit.  I found this report with a most gruesome title. After spending an hour or four attempting to capture the information, the horror of it, in a lecture, I suddenly realized how much better it would work to let the kids capture and represent the data themselves.

So after a brief lecture on cotton ginning, before and after, the students get the second page of the report, with the slave census data from 1790 through 1860. I always assign states by group–the eleven eventual confederate, the four border, and New Jersey for contrast, so usually each group gets four states.I then go through a brief review of Percent Change (“change in value over ORIGINAL value”, please) .

The assignment: For each state, calculate the percentage change each decade. Create Create a column graph showing the real change each decade, with the percentage change shown at the top of the column.

Once all four states in the groups are graphed, compare the growth rates.

The work so far has been done on whiteboards. Some of the whiteboards are small, for personal use. In other cases, the students did the work directly on my whiteboard walls.


Student work: Louisiana slavery growth, 1810-1860


Student work: Georgia slavery growth, 1790-1860


Student work: North Carolina slavery growth, 1810-1860


Student work: Alabama slavery growth, 1800-1860

Right about now, the students realize it’d be much easier to compare the growth rates if they’d used a common scale. Meanwhile, I’d found it difficult to group the states in such a way that each group got a representative sample of growth rates.

In prior years, I’d just lectured through some examples. But my class was much more manageable this year, and for some reason I realized Oh, hey. A teachable moment.

Their “statistics of slavery” handout was doublesided with graph paper. After everyone had finished their group of graphs, I took pictures of any small whiteboard graphs and displayed them on the smart board.

The assignment: quickly graph a line sketch representing the slavery trends in each states using CONSISTENT AXES.  x is year, with  1790 as x=0, or the y-intercept. y is the number of slaves, using 100K chunks through 500K.  No need to capture specific percentage growth, but the graph should reveal it. Something in between “graph every single point” and “just connect the beginning and end value.”

They did really well. A few of them forgot what I said about consistent axes–and mind you, I said this some EIGHTY TIMES but no, I’m not bitter.

SDAInconsistent SDAConsistent

Happily, most compilations got the full 5 of 5, just like the kid on the right (you can see where I corrected his first two).

So these graphs really allowed for informed discussion. (A couple students said “Wow, I actually get slope now.”)  The students were able to identify states that saw tremendous growth vs states with slow or static growth.

Why would states have different growth rates? I reminded them of the national ban on slave trade. Where would slaves come from? And so to the domestic slave trade, another cheerful topic. Unlike the Caribbean slave population, slaves in North America increased their population through natural increase. States that cultivated tobacco exhausted the soil and, as Thomas Jefferson put it  in a letter to Washington, “Manure does not enter into this [soil restoration], because we can buy  an acre of new land cheaper than we can manure an old one.”  People just up and moved, or bought more land, when the productivity dropped, and so the state populations declined. Virginia, Maryland, Kentucky, and North Carolina, tobacco states all, sold their excess slaves to the cotton states.

Interesting note 1: Washington and Madison were both passionately interested in saving Virginia’s soil. Washington abandoned tobacco early, converting to wheat and other less damaging crops. He consulted with many English experts on best practices in soil management. Madison tried to spearhead agricultural reform, but ran up against the southern dislike of centralization.

Interesting note 2: Virginia was a southern agricultural powerhouse despite its reduced tobacco crop, but its primary product was wheat, produced primarily by non-slaveholders in Shenandoah Valley, not tobacco or cotton produced by slaveholders. (Remember, Jimmy Stewart’s Anderson clan wasn’t interested in fighting for the Confederacy.)

Studying slavery reminds me of how seemingly obvious goodness probably wasn’t. So, for example, the south had constraints on manumission. Slaveholders couldn’t even free their slaves if they wanted to! Slave states didn’t want them setting a bad example! Except the constraints existed in no small part because slaveholders dumped older slaves incapable of work, putting indigent elderly slaves  with no family and no means of supporting themselves out on the street. Most of the manumission laws specified age and remuneration requirements, and most didn’t ban the emancipation of young, healthy slaves. So manumission constraints were at least in part about protecting elderly ex-slaves. But would a slave  rather be free, even if impoverished, than living as property?

Or the debate about ending the slave trade, during the Constitutional Convention, when George Mason gave a fine speech, accurately laying out the arguments against slavery–it discourages free labor, gives poor people a distaste for work done by slaves, turns slaveowning men into petty tyrants.  And then General Pinckney says, yo, fine talk from a Virginian, whose huge slave population instantly gets more valuable if we stop bringing in new ones.

What was Pinckney saying? The kids were mystified.

“Why would Virginia’s slaves get more valuable?” asked Eddie.

“Well, remember, this is banning slave trade. Not slavery. The Constitution didn’t give the federal government the right to ban slavery. So if slavery still existed, but no new slaves were being imported, the only slaves being created would be here in America.”

“Yeah, but I don’t see what makes them more valuable?” Jia was confused.

I paused. “Think about supply and demand. What would banning slave trade do to supply?”

“It would go….down.” Jun.

“Right. But demand isn’t decreasing. South Carolina, Kentucky, Georgia, they need slaves.

“They won’t be able to get anymore, though, because there won’t be any more slave trade,” offered Lee.

I stopped moving, wait until eyes are on me. (Teaching’s all about the performance.)

“There will be more slaves. The slaves themselves are having children, right?” I had barely gotten the words out when Lee figured it out, and he literally gasped.

“Yeah. It’s horrible. When the federal government banned slave trade, Virginia had more slaves than any other state. And thanks to lousy farming practices, its land wasn’t much good for tobacco. But as slaves met, married, and had children, lo! the Virginians had a ready made product for sale.” More kids got it and groaned.

“That’s where the phrase ‘sold me down the river’ came from. The phrase means to betray someone. But originally, it referred to a slave whose Virginia or Kentucky owner sold them to the cotton plantations in the deep south, Mississippi or Alabama.”

“So banning slave trade was done to increase the value of slaves?”

“I’m…pretty sure that’s not true. Remember that before the cotton gin came about, many of the founding fathers really did seem to think slavery would fade out, although they were fuzzy on how that would happen. But certainly, South Carolinians would be the ones to identify the market opportunity for another state.”


Another little data analysis activity, done earlier than the slavery stats above: read a series of Wikipedia entries to determine when Northern states freed their slaves, then create a timeline with color-coded data. “I” was banning importation, B meant banning slavery, (“g” meant ban was gradual).    All students had to color code the dates for importing bans and slavery bans. This student came up with the idea of an identifier for those states that gave blacks the vote, and those that restricted the right to vote, particularly after the fact.

Anyway, I wanted the students to realize that organizing data can lead to insights. In this case, the bulk of the Northern states banned importation and slavery in the same 20 year cluster. New York and New Jersey stand out in sharp contrast. Another oddness: Rhode Island banned slavery earlier than it did imports, for the obvious reason that Rhode Island was the epicenter of the slave trade.


I never liked all the stories about slaves quarters, and jumping the broom, and so on. Not that they aren’t interesting, but they don’t carry the weight of data, of seeing the huge numbers. Of realizing that manumission might be a way to dump non-productive workers, or that ending slave trade might be a business move to increase property value.

It’s too much like Anne Frank, or the Anne Frank that her loving dad created. Whenever I hear kids say “Oh, I identified with Anne sooooooo much!” I want to smack something. She lived in an attic for two years. She was then sent to a concentration camp where she held onto life for six month and then died of typhus, her body crawling with lice, just a month or so before liberation. Identifying with that level of suffering is well-nigh impossible, so spare me your virtue signaling, you teen drama queen. Hrmph.