Friday, May 6, 2011

Slavery and Mobility

One of the great innovations in visual information display was demographic maps created by Alexander Dallas Bache of the U.S. Coast Survey in 1860. These showed visually the concentration of slavery in narrow regions even within the South, and were among the most powerful tools of abolitionists. Blache was the first to use the now-familiar method of shading regions to show their demographic traits.



I was struck looking at this map how closely it resembles the current mapping of non-Hispanic blacks in the U.S. (Year 2000 data; from Social Explorer). Look closely at some part of both maps; you'll find that even at a county-by-county level, the concentration of blacks in 2000 is closely related to the slave population in 1860.

3 comments:

Mama Beth said...

...which tells us????

Carol L. Douglas said...

I've seen the slave map before, but I'd like to see comparable images for the north. While you may not see social mobility from these images, it may be inaccurate; I think we might see similar racial concentrations across the Rust Belt cities.

Chops said...

These type of maps are mainly good for rural areas, Carol. There are high urban concentrations of blacks everywhere in the country; however, they don't show up much on county-level maps. A better technique for mapping urban populations is circles of different sizes, so that one recognizes the difference in population size between, say, Rochester and Boston, not just their land area.