Istanbul Tram Ticket: for a full sized image click here
nice map of the different routes in French, along, with the Golden Horn labelled Corne D'or). A map from the early Republican period (left) shows much the same system, but of course with the names no longer written in French.
In the 1950s, many of the tram lines were torn up to make room for cars on the relatively narrow streets. The problems were quickly apparent, hence the following map (below) of Istanbul's transportation needs in 1958. It appears a vast majority of the city's movement then took place on a north-south axis from Şişli to Eminönü. (Another map shows the popularity of different ferry routes. Eminonu-Kadikoy was by far the most used, with virtually no one going to Üsküdar from Beşiktaş or elsewhere)
Sources: Ticket courtesy of the Sunday Antikaci Pazari in Kurtulus. Republican era map from Lelik Gulersoy's Tramvay Istanbul'da, Istanbul Kitapligi, 1989. Transport study from Istanbul Trafik Etudu - Traffic Survey, Bayindirlik Bakanligi Karayollari Genel Mudurlugu, Planlama Fen Heyeti. Schematic for the new tram line from Istanbul Ulasiminda 50 Yil, published by the Karayollari Genel Mudurlugu (Ankara) in 1974.