Complex sentence: When electric street railways became ubiquitous, it was only used in those cities that did not permit overhead wires, including London, Paris, Berlin, Marseilles, Budapest and Prague in Europe and parts of New York City and Washington DC in the United States.
Split into simpler sentences: When electric street railways became ubiquitous, it was only used in those cities which did not permit overhead wires. These included London, Paris, Berlin, Marseilles, Budapest and Prague in Europe and parts of New York City and Washington DC in the United States.