Robert Lewis Jefferson was born about 1786 in Buckingham County, Virginia. He married twice:
Called "Lewis" by his family, Robert Lewis Jefferson was one of Randolph and Anne “Nancy” (Lewis) Jefferson's younger sons. Clear evidence of his familial name is a letter written in 1807, from Randolph to his brother, Thomas Jefferson, which was addressed: "Mr. Thomas Jefferson; pr son Lewis; Monticello; To the Care of Mr. Dinsmore." Although official records tend to record him as Robert L. Jefferson, he was apparently called Lewis until his death. On an Albemarle County survey for Matthew M. Harris dated April 5, 1858, his neighbor was identified as "Lewis Jefferson."
On his death record, dated March 13, 1858, Lewis’ age was given as 72. If this is correct, he was probably born at Snowden, Buckingham County, Virginia in about 1786. The 1850 census, enumerated in November, records that he was 63 years old, suggesting he was born in 1787.
On October 10, 1812, Lewis Jefferson married a Miss M. Jordan in Nelson County, Virginia. They were likely married at the home of her father, William Jordan, who owned land on Elk Island Creek in Nelson. Her first name remains unknown. In about 1814, their only child, Elbridge G. Jefferson, was born. M. (Jordan) Jefferson died before 1820.
In 1828, Lewis Jefferson completed the purchase of a 531-acre plantation on Sharps Creek in Buckingham County, Virginia. On October 6, 1828, in Albemarle County, he married Elizabeth Ann "Bettie" Moorman, with whom he had one daughter, Mary Elizabeth "Bettie" Jefferson. Later, Lewis gave the Buckingham farm to his son, Elbridge, and removed to Albemarle, to operate his wife’s plantation, Rock Castle.
Robert Lewis Jefferson died from cancer on March 13, 1858, probably at Rock Castle, near Warren, Virginia. His death was reported by his son-in-law, Albert Gantt. Lewis’ parents were recorded as Randolph and N. (Nancy) Jefferson. 
Mayo, Bernard and James A. Bear, Jr., eds. Thomas Jefferson and his Unknown Brother. Charlottesville: University Press of Virginia, 1981.
Yeck, Joanne L., The Jefferson Brothers. Kettering, OH: Slate River Press, 2012.
1820 US Federal Population Census, Nelson County, Virginia
1840 US Federal Population Census, Buckingham County, Virginia
1850 US Federal Population Census, Albemarle County, Virginia
1828 Land Tax, Buckingham County, Virginia
Marriage record, Nelson County, Virginia
Marriage record, Albemarle County, Virginia
Death record, Albemarle County, Virginia
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