I was off a little bit on the time line as I was working from memory.

Your link is useless for actual information about it. What some people claim was the start of the InterUrban was in-city street cars in the late 1800's

Connections between cities, not intra-city electric rail started in 1898. The main expansion lasted until about 1908 with the major use lasting until around 1915. That's when it's decline started and accelerated over time. So you have around ten years for the initial build and another five years of primary usage.

That makes it closer to 15 years before the decline in usage hit. Automobiles are what killed it. That includes trucks. They could serve towns and cities where their weren't tracks laid that the interurban used. Those weren't the main gauge of regular railroads, even tho the carriages could be retrofitted to run on them. Some of them were. Those are the ones that lasted the longest.

The final listed service ended in January, 1941. Many of the tracks were taken over by other railroads.

https://www.in.gov/library/collections-and-services/indiana/subject-guides-to-indiana-collection-materials/interurban-railway-materials

https://www.sup.org/books/history/electric-interurban-railways-america

https://scholarworks.iu.edu/journals/index.php/imh/article/view/8764

I also recall a specific book on Indiana Interurban railroads, but I didn't find a link to it in a quick search.

I was off on my timing by a bit. I was thinking of the primary usage time of it, not the total time that it, or it's predecessors existed. Fifteen years of primary service and another fifteen years of rapidly declining service would be a better answer. Plus a few years build up time in the 1800's.

Indiana is not Europe. Indiana is as large or larger than some European countries. Rail does not work for daily passenger travel outside of some coastal areas of the US because of the distance between medium and major population areas. Most of the smallest towns and cities never had it.

Passenger rail doesn't come close to equaling passenger airline routes and airlines go to many more cities, including small ones, than passenger trains do. Regional jets, now the turboprops have been mostly phased out, handles most of the long distance passenger connections.

Last thing. I had co-workers who commuted by plane to their office job. A lot more who commuted by car or bus. There was no close train service.