You have likely already located the following... however, if you have not... then perhaps it will give you a lead to follow down at the Duluth Public Library...


http://dplreference.wordpress.com/

News Tribune
July 9, 1967 

Starting at 1 p.m. today, 53 boys will race in the Duluth Soap Box Derby championship on the Hartley Field Derby Track.  The track is one of just eleven in the country owned by a local derby.

Hartley had/has a derby track? All the times I have spent wandering the trails there, I don't remember noticing any overgrown asphalt. Where is it located?

Yes, I found the website.  I probably should have done a google search before posting my comment/question...

Former Duluthian Bo Conrad won the national Soap Box Derby title some time in the 1960s. I think his mom is still in town.....

Bo's mother has passed, but his older sister Dorthy Conrad still lives in town and has an archive of some sort.