1. Population Change and the Persistence of the Legacy of Slavery
Heather A. O’Connell
Katherine J. Curtis
Jack DeWaard
I’d like to quickly acknowledge Katherine Curtis, who is here in the audience, and thank you all for having me here. It’s a pleasure to share our work with you. In this project, our focus is on better understanding how the legacy of slavery has persisted over time, particularly the disruptive influence of population change.

2. Legacy of Slavery
Social and institutional remnants of the ideology used to justify slavery
Before I get any farther, what is the legacy of slavery?
Define…
Focus on place and spatial distribution of outcomes.

3. Legacy of Slavery
Social and institutional remnants of the ideology used to justify slavery Empirical evidence (poverty inequality, school segregation, political attitudes, etc)
Previous research has established a connection between historical slavery and a variety of contemporary outcomes, including…
Scholars argue that this provides evidence of a legacy of slavery, one that supports exacerbated levels of black-white inequality and overall conservative political climates that extend far enough to effect even the implementation of different types of health care measures (new SSM paper).
Seems plausible, especially given attempts to explain the initial association using a variety of contemporary measures, but the argument is based on an association between one variable from 1860 and another measured 150 or more years later.

4. Legacy of Slavery
How does it persist over time? Intergenerational transmission Embedded in place
So then one of the big questions plaguing this literature is: how does something that happened so long ago still matter today? How does this social structure persist over time? Particularly in the face of so much potential change.
Others have developed and tested arguments suggesting the transmission of norms and attitudes from one generation to the next, which helps sustain slavery’s legacy. Similarly, Molotch et al have developed a more general argument detailing how places develop an identity and how early decisions can make it difficult – although not impossible – to deviate from that initial track.
This previous research provides a general argument for how the legacy of slavery could persist, but our question is more DOES it persist, particularly when we think about the many changes that have taken place.

5. Research Question
Does population change disrupt the link between historical slavery and contemporary black-white economic inequality?
In this research we focus on one important type of change – population change – because it has the potential to disrupt the social dynamics that have been hypothesized to be a part of the legacy of slavery and its transmission over time.
That is, do high levels of population increase or decrease disrupt any relationship between historical slavery and contemporary black-white economic inequality? And conversely, is the legacy of slavery relationship strongest in places that have experienced relatively little population change?

6. Data
County-level, US South 1860 Population Census, concentration of slaves
There are several important pieces of data required to address this kind of question, all of which are at the county-level and only for southern states. This focus is consistent with previous research and our attention to how historical institutions – namely slavery – become embedded in place and subsequently persist over time.
First, is the data we use to proxy the strength of any contemporary legacy of slavery, which is the concentration – or proportion – of slaves in the total population for a county in This, too, is consistent with previous research.
Second, we use the American Community Survey estimates to estimate black and white poverty rates, among other contemporary characteristics of a county, including black population concentration, industrial composition, and unemployment.
These two pieces represent our focal independent variable and our dependent variable. But we also need population change.

7. Data
County-level, US South 1860 Population Census, concentration of slaves American Community Survey, contemporary black and white poverty rates
There are several important pieces of data required to address this kind of question, all of which are at the county-level and only for southern states. This focus is consistent with previous research and our attention to how historical institutions – namely slavery – become embedded in place and subsequently persist over time.
First, is the data we use to proxy the strength of any contemporary legacy of slavery, which is the concentration – or proportion – of slaves in the total population for a county in This, too, is consistent with previous research.
Second, we use the American Community Survey estimates to estimate black and white poverty rates, among other contemporary characteristics of a county, including black population concentration, industrial composition, and unemployment.
These two pieces represent our focal independent variable and our dependent variable. But we also need population change.

8. Data
County-level, US South population counts, black and white population change Time constant geographies
For that, we use our third primary data source, which is the population counts for each decade starting in 1880 and ending with We expect that the impact of population change may differ depending on whether that change is in the black or the white population, so we use population estimates for both groups.
One important technical note: In order to create our population change estimates from one decade to the next, we first had to create time constant geographies. There were a slue of boundary changes during this time period, so creating time constant geographies is critical if we want our estimates to reflect real population change and not just fluctuations in the area of county. I would be happy to discuss the details of this process if you’re interested, but for now I reassure you that all data have been adjusted to reflect the same time constant geographies.

9. Variables
Dependent Variables, 2015 (5-year) Black minus White poverty rate Black poverty non-Hispanic White Poverty

10. Variables
Population change, Focus on growth vs. decline Three time periods Black and White
Break down the specific components.

11. Methods
Regression analysis, interaction Negative interaction suggests population increase weakens the legacy of slavery
Our general methodological approach is to use an interaction in a multivariate regression. Specifically, we need to interact population change with historical slavery to assess the extent to which population change alters the expected positive association between slavery and contemporary racialized poverty outcomes.
A negative interaction…
Conversely, and counter to our expectations, a positive interaction would suggest…
A non-significant interaction would suggest population change has no impact the extent to which the legacy of slavery persists or not, which would suggest it is a pretty robust or sturdy feature of place.

12. Methods
Regression analysis, interaction Negative interaction suggests population increase weakens the legacy of slavery Positive interaction suggests population increase enhances the legacy of slavery
Our general methodological approach is to use an interaction in a multivariate regression. Specifically, we need to interact population change with historical slavery to assess the extent to which population change alters the expected positive association between slavery and contemporary racialized poverty outcomes.
A negative interaction…
Conversely, and counter to our expectations, a positive interaction would suggest…
A non-significant interaction would suggest population change has no impact the extent to which the legacy of slavery persists or not, which would suggest it is a pretty robust or sturdy feature of place.

13. Methods
Spatial data analysis techniques Moran’s I, residuals I = .08, p < .001 Results from error model are consistent
We use spatial data analysis techniques to address the potential impact of spatial positioning on our regression results. Specifically, we tested our model residuals for spatial correlation using the Moran’s I statistic. We found minimal but significant levels of spatial correlation. However, the results are virtually identical when using a spatial error model, which is consistent with the substantively minimal Moran’s I statistic.
We have chosen to present the more parsimonious OLS models, but the spatial error model results are also available.

14. Results Decadal Population Change, US South
The first step of our analysis is to analyze population change in our study area.
For the South as a whole, minus OK because it was not a state in 1860 and therefore does not have slave data, we find the following trends in population change for the total, black, and white populations. We divide the 13 decade pairs into three time periods. These time periods roughly correspond with the Great Migration, and general temporal trends in population within the US South.
The region experienced population growth throughout the time period, but it was at its peak in the earliest decades. We see a decrease in the degree of growth for both blacks and whites, but this slowing of population growth is most pronounced for southern blacks. Their growth rate remains substantially lower than that of whites until the 1970 to 1980 decade pair. The growth rate between 1970 and 1980 is nearly equal for blacks and whites. But then the two diverge again in most recent decades.
When characterizing population change, we also wanted to be sure to understand the spatial nuances, so we look at the county-level population change associated with each of these time periods.

15. Results Early Black Population Change
This first map is of black population change during that early time period. Despite there being an overall high level of population growth in the region for this time period, there are clearly differences in the extent to which that regional trend manifested locally.
Go through the three periods relatively quickly – just to give a sense
Early

16. Results Middle Black Population Change
This first map is of black population change during that early time period. Despite there being an overall high level of population growth in the region for this time period, there are clearly differences in the extent to which that regional trend manifested locally.
Go through the three periods.
More importantly for our analysis is the fact that local population change often diverged for blacks and whites –
Middle

17. Results Recent Black Population Change
This first map is of black population change during that early time period. Despite there being an overall high level of population growth in the region for this time period, there are clearly differences in the extent to which that regional trend manifested locally.
Go through the three periods.
More importantly for our analysis is the fact that local population change often diverged for blacks and whites –
Recent

18. Results
White Population Change
White map, early
Early

19. Results
White Population Change
White map, early
Early

20. Results
White Population Change
White map, early
Early

21. Results Table 1. Legacy of Slavery Relationship, Net of Controls
Inequality
Black Poverty
White Poverty
Coef SE
Slave Concentration, 1860
-.03
.03
-.04
-.02 *
.01
* p < .05; ** p < .01; *** p < .001
Baseline regression results – black poverty, white poverty, inequality.
Importance of white advantage. Consistent with other research.
Just going to show the interactions for three dimensions of population change.

22. Results Table 2. Black Population Increase, Middle Period Inequality
Inequality
Black Poverty
White Poverty
Coef SE
Slave Concentration, 1860
-.02
.03
-.07  *
-.05
***
.01
Black Population Increase
.00
.02
-.03
.01
-.02
***
Interaction
-.03
.04
.03
.05
***
.01
* p < .05; ** p < .01; *** p < .001
Interaction results – black population change, middle period
Focusing first on the white poverty model where we see persistent legacy effects, black population increase fully explains this association – interaction suggests that legacy only persists where black population declined in the middle period. The transmission of the legacy of slavery was fully disrupted in counties that experienced black population increase.
Interestingly, suppressing effect for black poverty model…

23. Results Table 3. White Population Increase, Middle Period Inequality
Inequality
Black Poverty
White Poverty
Coef SE
Slave Concentration, 1860
-.04
.05
-.10  *
.04
-.06
***
.02
White Population Increase
-.03
.02
-.04 **
-.02
.01
Interaction
.02
.04
.07
.05 **
* p < .05; ** p < .01; *** p < .001
Interaction results – white population change, middle period
Very similar to what we observed for black population change in the same middle period – something more general about experiencing population increase during this time period? May be especially unique, and be more reflective of other place characteristics rather than suggestive of the population change having an impact. Great Migration – most southern counties were on the decline.

24. Results Table 3. White Population Increase, Early Period Inequality
Inequality
Black Poverty
White Poverty
Coef SE
Slave Concentration, 1860
.11
.07
.09
-.02
.04
White Population Increase
.10 **
.03
.00
.01
Interaction
-.14 *
.07
.00
.03
* p < .05; ** p < .01; *** p < .001
Interaction results – white population change, early period
Most consistent with our expectations. May help explain weak baseline relationship for inequality. Driven by changes in black poverty relationship

25. Discussion
Legacy has declined, but perniciously linked to white advantage Population change helps explain where this history still matters Legacies are persistent, but not permanent
Legacy of slavery is argued to be an important part of understanding contemporary society – particularly connected to the persistence of white advantage.
Unique extension of Gabriel and Tolnay – more time and race for a more comprehensive capture of population change. We provide new evidence suggesting…
Implications – legacy is social and can be disrupted?

26. Limitations and Extensions
Treats different dimensions of population change as if they are independent Population change, not migration At what point does the legacy of slavery start to diminish?
Limitations and extensions
Multiple dimensions simultaneously
Focus specifically on migration in supplemental analyses, but only for decades starting in 1950…
At what point does the legacy of slavery start to diminish?
Additional limitations:
Large geographies – are they socially meaningful? Likely not. Could conduct sensitivity analyses without large clusters
Finally, our study relies on a proxy of the legacy of slavery, namely historical slave concentration. Scholars argue this measure reflects the extent to which slavery ideology has become embedded in place, such that a higher concentration of slaves would increase the social necessity of norms and strict ideas about race that reinforce inequality. As a result, we would expect these places to retain remnants of this ideology via the legacy of slavery argument, but ideally we would have a direct measure capturing the contemporary manifestation of that legacy rather than a historical proxy. That, I believe, will be the next big challenge in this literature.