https://en.wikipedia.org/wiki/Portland_Streetcar
https://en.wikipedia.org/wiki/Portland_Streetcar#Proposed_expansions
https://en.wikipedia.org/wiki/Portland_Streetcar#Comparison_with_light_rail
https://en.wikipedia.org/wiki/Streetcars_in_North_America#Second-generation_streetcar_systems
https://jfdatalinks.blogspot.com/search?q=streetcars+and+trams