This map comes from the 1915 “Report on Detroit Street Railway Traffic and Proposed Subway.”
On East-West Lines:
“These lines carried 130,553,415 passengers (including transfers) in 1914. Here again it must be noted that all of this traffic was not carried across the center of the city, but the figures give the relative importance of this group of lines.”
On Interurban Lines:
“These lines provide a valuable function in connecting the city with a very widely distributed interurban district, and also run a through service to cities of considerable size.