I knew I'd heard recently about someone brilliant who had obsessed over bus tickets. Thanks for helping me recall it.

A recent episode of Radiolab, dated August 27, 2019, introduced a large audience (including me) to another podcast, The Memory Palace:

https://www.wnycstudios.org/podcasts/radiolab/articles/memor...

With that strong endorsement I began going through the whole back-catalog of The Memory Palace, and Episode 36, dated January 7, 2011, “six scenes from the life of william james sidis, wonderful boy”, talks about Sidis' obsession with bus tickets. Or maybe more precisely, streetcar transfers.

http://thememorypalace.us/2011/01/six-scenes-in-the-life-of-...

I think it said he figured out ways to traverse great distances on a single fare by connecting transfers. That kind of graph traversal thinking strikes me as ahead of its time for the age of streetcars, and could plausibly have led to some interesting places.