The building I work in was once the carbarn, workshop, and general offices of the old Minneapolis Street Car system, - back when the street cars were horse drawn.

I'm sure that by the time the street cars where demolished or sold, ridership was low and maintaining the rails was deemed too expensive. Cheaper to run buses on streets that the city already maintained, especially since GM was providing buses at huge discounts in order to displace the street cars.

Interesting that drivers initially had to share the streets with trolleys, now many gripe that "streets were meant for cars" when having to share them with bikes.