Try, just for a minute, to make a list of all the things this woman has seen and lived through, technological developments, legal developments, geo-political development. Today, there are in the order of 50,000 centenarians living in the U.S. and our history is so incredibly short. It's 2016. Next year is the 500th anniversary of the Reformation, if you count from Luther's 95 Theses (which most people do, though there are certainly arguments to the contrary). Our country turns 240 this year if you count from the Declaration of Independence, 229 if you count from the ratification of the Constitution, 151 if you count from the end of the Civil War. The last person to sail on the HMS Beagle with Darwin died in 1914. The last veteran of Ft. Sumter died in 1919 when Susannah Jones was 20. The last witness of Lincoln's assassination at Ford's theatre died in 1951, when Jones was 52. The last U.S. and Native American veterans of the Little Big Horn died in 1950 and 1955 respectively, when Medicine Crow was in his forties. Geronimo died in 1909. Joe Medicine Crow was not born yet, but of course Susannah Jones was 9. Like one of my sons is right now.
*The last living American who had been a "legal" slave under the chattel system of the South was Sylvester Magee, who died in 1971 (the historical reality of "Slavery by Another Name" is a different question).