In many cities colours were used to distinguish different routes of public transport. I am not so much concerned here with those cases (as the London Underground) where maps use specific colours, but only in those were the vehicles display colours in some way. I am trying to accumulate here as much information as I can find, primarily focussed on European companies that do or did operate electric trams. The following cities are covered in one way or another. For many cities I can only provide snapshots. City names are given in the local language.