I found my copy of "The Plains & The People". On pages 283 & 284 I found the following: James Loudon immigrated from Scotland & settled in LA in 1797. His wife was Elizabeth (probably Mary Elizabeth) & they had William, James, Nancy, Sarah, John & David (who was my ggg grandfather).
William married Sarah and they had Elizabeth (b 1829) who married Norman Black (b 1828 in Tenn)& their son was Loudon Black (b. 1856, no rec.). If I find more I'll let you know.