The history of the oldest Porto tramcars is very complicated, but partly also obscure. They were hauled by both mules and steam locomotives. Later part of them were transformed into electric trams while the others continued as trailers of the electric trams. The majority was disposed of during the second decade of the twentieth century, but a few even made it into the first half of the 1960’s.
This page is about the vehicles, there are separate pages about the history of the mule and steam tram networks.