I, too, am interested in these families because my Willis Barton has similar DNA to some men with the Cox surname. Willis was in Pendleton District until between 1820 and 1830 when he moved to Hall Co., GA. Have any of the Pickens County Cox descendants had a yDNA test?
In 1800 Pendleton District (Pickens Co., SC was carved from Pendleton), there were a number of Cox families.
C200 COX William M-032 050 20 <-- pg number
C200 COX Edward M-032 050 20
C200 COX Susannah M-032 050 20
C000 COX Elizabeth M-032 050 26
C200 COX John M-032 050 26
C000 COXE William M-032 050 32
C200 COX Henry M-032 050 31
C000 COXE George M-032 050 33
B635 BARTON Joseph, j M-032 050 34
C200 COX Phillip M-032 050 35
B635 BARTON Moses M-032 050 35 [son]
B635 BARTON James M-032 050 35 [son]
B635 BARTON James M-032 050 39 [father]
C200 COX William M-032 050 42
C200 COX James M-032 050 47
C200 COX John M-032 050 47
C200 COX Mary M-032 050 47
[http://files.usgwarchives.net/sc/pendleton/census/pend1800.txt]
Moses and his brother, James, were listed on page 35 along with Phillip Cox. One of these 4 Barton men should be the father of my Willis Barton, but he doesn't match the DNA of any of the Pendleton/Greenville, SC Bartons, yet his DNA is very close to members of the Cox family who took this test. I don't know where they are from. It could be Pennsylvania for all I know.
I haven't researched the Cox families of Pendleton, but would be interested in learning more about them.
Joseph and Indiana Rebecca Barton's son, David, married Elizabeth Cox.
http://www.bartondatabase.info/getperson.php?personID=I9358&tree=gbtree
Pages 411 - 413: Baveaster Barton for £10 Sterling sold to John Cox 40 acres bordered by Thomas Turner, John Simpson, and the said Barton, granted William Lesley. Dated: 21 mar 1803.
Witness: Edward Cox, John Hall
http://www.stockmanfamily.net/coxlan.html