It appears that Basecamp library files have the .bclibrary extension.
Assumed the default library would be in the Library folder under my User Profile, But searching for files with the .bclibrary extension turns up nothing.
I'm having an issue with installing the map from my device to my computer. Went partway through process but it failed when device disconnected from my computer. Now the map won't install. Wondered if I could remove the partially installed map from the default library location.