One of the largest/best developed Interurban networks was in Indiana.

Here is a map

The hub of the network was in Indianapolis, which had the world's largest interurban terminal:

My memory might be failing me, but I seem to remember this structure still being used by the city bus system in the early 60s when we would visit relatives in Indpls.

My mother has told me stories of going out on dates in the early 1940s and taking the interurban from Kokomo to Indpls. I grew up in Indiana and remember older folks talking about their fond memories of the interurbans and lamenting their demise.

Sadly, that structure is long gone, and Indy now has perhaps the worst public transportation of any US city its size. Indianapolis does, however, have an ambitious plan to make its downtown more bike- and pedestrian-friendly:

http://www.streetsblog.org/2007/10/15/indianapolis-paves-the-way-for-bik...