Correction: Nathan is NOT the youngest finisher!
Ron Bartell (SPS finisher #21 in 1982) writes to inform us that Nathan is not the youngest finisher of the SPS List. That honor belongs to Frannie Hoover, age 20, in 1983. Her brother, Nathan, finished at age 22 years 4 months in 1981.
Assuming there are no others, that would make Nathan the third youngest at 22 years 9 months.
Thanks to Ron for pointing this out and we are happy to hear any other comments or corrections at firstname.lastname@example.org.