Here is the list of Abraham Lincoln's descendants who lived died out in 1985.
Robert Todd Lincoln Beckwith (July 19, 1904 – December 24, 1985) was the great-grandson of Abraham Lincoln.[1] In 1975, he became the last undisputed descendant of Lincoln when his sister, "Peggy" Beckwith, died without children.[2]
His grandfather was Robert Todd Lincoln who had three children:
Mary "Mamie" Lincoln (October 15, 1869 – November 21, 1938)
Abraham Lincoln II (nicknamed "Jack") (August 14, 1873 – March 5, 1890)
Jessie Harlan Lincoln (November 6, 1875 – January 4, 1948)
Of Robert's children, Jessie Harlan Lincoln Beckwith (1875–1948) had two children, Mary Lincoln Beckwith ["Peggy" 1898 – 1975] and Robert ("Bud") Todd Lincoln Beckwith (1904–1985), neither of whom had children of their own.
Robert's other daughter, Mary Todd Lincoln ("Mamie") (1869–1938) married Charles Bradley Isham in 1891. They had one son, Lincoln Isham (1892–1971). Lincoln Isham married Leahalma Correa in 1919, but died without children.
The last person known to be of direct Lincoln lineage, Robert's grandson "Bud" who was the son of Jessie mentioned about. Bud died in 1985 without children.