The US Census Was Tracking Freedom All Along
- 1838 Black Metropolis
- Nov 17
- 5 min read
Updated: Nov 18
TLDR:
US Census data makes visible the movement of the liberation of Black people from enslavement in the 19th Century.
Over 400,000 people liberated from enslavement over a 70 year period.
An average of 1000-2000 freedom seekers through Philadelphia, per year, for 70 years.
See our 1838 Population Statistics
See our Free Black Population Growth
The US Census Reveals the Liberation of Black People from Enslavement
When people look at a chart like this one - showing the free Black population in Pennsylvania from 1790 to 1860 - they often see the blue line going up and think, “Wow, the Free Black population was growing fast.”
But here’s the thing: it wasn’t growing fast because of natural birth rate. And it wasn’t due to immigration from Africa either.
To really understand this visual, you have to know what “normal” looks like. A natural biological population growth rate is about 1–2% per year in a stable community. That’s what you’d expect if the population stayed in one place and simply had children at a steady rate.
But Pennsylvania’s free Black population wasn’t growing at 1 to 2%. It was growing at 25%, 40%, and even 50% from one census decade to the next.
That kind of jump doesn’t happen naturally. It happens when people are moving.
And before emancipation, before the Civil War, before the end of slavery - the only way large numbers of Black people were moving north was through emancipation efforts, like self-liberation and the Underground Railroad.
So what does this chart actually show?
The blue line (population numbers) climbs because more and more Black people were living free in Pennsylvania each decade.
The green line (growth rate) tells the real story:
1790–1800: +123% - This is mostly due to Friends Manumissions and Haitian emigration.
1800–1810: +54%
1810–1820: +34%
1820–1830: +25%
1840–1850: +41%
1850–1860: +6%
When you see growth rates that high - especially before 1865 - you’re looking at a story of movement toward freedom.
Not immigration. Not birth rate.
Freedom-making.
Black people were not immigrating from Africa in large numbers in the 1790s, 1800s, or 1810s - the transatlantic slave trade brought enslaved people to the South and the Caribbean, not the free North.
And the natural birth rate can’t produce decade-to-decade 40–120% jumps.
So the increases you see here are mainly:
Self-liberation -people escaping slavery via the Underground Railroad or other means
Gradual abolition laws freeing people over time
Movement from the Upper South into free states
Networks of Black churches, Quakers, schools, and communities that made freedom possible
This growth is the human footprint of the Underground Railroad.
Then why does the growth rate decline later?
You’ll notice that after the early decades of explosive growth, the rate drops sharply in the 1840s and especially the 1850s.
This is not random. This is policy.
1793 Fugitive Slave Act already made escape dangerous.
1850 Fugitive Slave Act allowed marshals, kidnappers, and slave catchers to seize people without trial.
It could be that Free Black communities responded by moving outside of the US, this time to safer places outside the U.S.
Canada (Ontario in particular)
Trinidad
Haiti
Liberia
So when you see the growth rate fall to 6% in 1860, it’s reflecting:
forced movement
people fleeing the U.S. entirely to preserve their freedom
The chart is literally showing the pressure of the law on Black bodies.
Interestingly, DuBois's Philadelphia population chart from the Philadelphia Negro shows a population increase after 1850.
The same data set can be used to show how many free Black People were in the North vs. the South. If we subtract a natural population growth rate of 1% then we get about 247,000 Free Black people in the North by 1860.
What does this mean for Philly? Estimating Underground Railroad Traffic Through Philadelphia
This table (see the spreadsheet) takes the same population data you saw in the growth-rate chart and flips the perspective: Instead of asking “How fast was the free Black population growing in the North?”, we ask:
“How many people likely passed through Philadelphia?”
Here’s the logic behind the table, step by step:
1. Start with the total free Black population in the North (Column B)
These numbers come directly from the census. Example: In 1800, there were 46,653 free Black people in the Northern states.
2. Estimate what the population would have been under normal conditions (Column C)
If a population grows naturally (births minus deaths), you usually get 1% to 2% growth per year.
The table uses 1% per decade to establish a conservative baseline.Why? To isolate actual movement - people becoming free and moving north - not biological growth.
So for 1800:
1% of 46,653 = 467 people (That’s the amount you would expect through natural population change.)
3. Subtract the natural growth to find the people who had to be freedom-seekers (Column D)
This is the key insight.
If the Northern free Black population jumped by 46,186 people between 1790 and 1800 - but only 467 could be explained by natural births - then:
The remaining 46,186 people most likely represent freedom-seekers.
This is the actual human movement behind the growth.
4. Calculate how many new freedom-seekers arrived each decade (Column E)
This shows the decade-to-decade increase in freedom-seekers.
It tells you the rhythm of the liberation.
Examples:
1800 → 1810: 30,098 people
1820 → 1830: 38,012 people
1840 → 1850: 25,074 people
These jumps reflect major political and geographic changes — manumissions, the rise of free communities, and changing routes as laws got harsher.
5. Estimate how many passed through Philadelphia (Column F)
Historians generally estimate that about half of all freedom-seekers came through Philadelphia because of its position:
Southern border state
Active Vigilance Committees
Large Black population
Church networks
Proximity to slave states
So if 38,012 new freedom-seekers arrived in the North between 1820–1830, we estimate: ≈19,006 passed through Philadelphia.
6. Divide that number by 10 to estimate the yearly volume through Philadelphia (Column G)
This gives the average number of people arriving per year.
These are the orange numbers on the right.
Examples:
1790–1800: ~971 people per year
1800–1810: ~1505 per year
1820–1830: ~1901 per year
1850–1860: ~1480 per year
This is the number of people who may have been passing through Black churches, homes, cellars, attics, back rooms of barbershops, and mutual-aid networks in Philadelphia every year.
The Big Takeaway
This data makes the movement visible, captured by the US Census.
Over 400,000 people liberated from enslavement over 70 years.
An average of 1000-2000 people through Philadelphia, each year, for 70 years.
It shows that the growth of the free Black population in the North only makes sense if tens of thousands of people were becoming free and moving north each decade - and that Philadelphia was one of the most important crossing points for that movement.
The numbers also match everything we know from Vigilance Committee records, abolitionist correspondence, and city directories: Philadelphia was a major engine of freedom.
Sources:
Wilber Sibert's Underground Railroad Collection https://ohiomemory.org/digital/collection/siebert/id/14280
Erin Bradford's complication of Census Data https://www.ncpedia.org/sites/default/files/census_stats_1790-1860.pdf
W.E.B. DuBois, The Philadelphia Negro https://archive.org/details/philadelphianegr001901mbp/page/48/mode/1up