Germany was altered in five ways by a ground-breaking €9 rail pass.

While the majority of Germans probably believed they were simply going about their daily lives, every weekend getaway, metro ride to work, bus trip to the store, and train trip to a lake to escape the record-breaking heat this summer were all a small part of a massive experiment: Germany's €9 train ticket.

It permitted unrestricted use of local and regional transportation throughout the entire nation and was created to provi....