Glascock County was created from the southern portion of Warren (and a tiny bit of Jefferson) in 1857.
Racial and population data for Glascock, Warren, Jefferson, Washington, Hancock 1860ff.
1860
Glascock 2400, 32% Black
Hancock 12000, 68%
Jefferson 10200, 60%
Warren 9800, 56%
Washington 12700, 52%
1870
Glascock 2700, 30%
Hancock 11300, 68%
Jefferson 12200, 65%
Warren 10500, 59%
Washington 15800, 52%
1880
Glascock 3600, 30%
Hancock 17000, 70%
Jefferson 15700, 64%
Warren 10900, 63%
Washington 22000, 57%
As you can see, the pattern's very old (though the Black proportion in Glascock has decreased since). Creation date is a bit too early for racial gerrymandering (during the half-century after the war, county creations in the south were usually done with an eye to racial figures - Long GA was formed from the White part of Black Liberty County. Vance NC was formed from the Blackest parts of its three neighbors to make those - all Black-controlled until then - Democratic-voting), so maybe it really ia a kind of "upland" place as Al guessed.
They have the
coolest name for a weekly local rag, btw.
