I do the same thing. For example, in the book I'm currently reading, I was looking at the maps showing Helena and Bozeman Montana with the mountains the hero had to cross.

The last book had the Exploits of Nelson Miles forcing the Lakota onto reservations just after Custer in 1876. Led me to look up the hstorical record.

There are 10 kinds of people.
Those that understand binary and those that don't.