In the early 1870s, an epizootic decimated the horse population of urbanized America (such as it was at the time): there are pictures of gangs of otherwise-unemployed men hauling New York's horsecars, for example. Suppose Andrew Smith Hallidie (he who designed the initial San Francisco system) had generated his technology as a function of the epizootic, about four to five years earlier (let's say 1872) and did so not in San Francisco but in New York?
Bear in mind that while New York has a much more rugged climate than San Francisco, it also doesn't have some of the topographical challenges that San Francisco does--and it does have one very favorable advantage: long, straight streets combined with a high population density. So let's say the first cable routes were laid on the north/south avenues of Manhattan before the Centennial. How would that have altered transit history later in the 19th century and beyond?
* Would it still remain for a successful Chicago installation to demonstrate that cable technology would work in a continental climate?
* Would Frank Sprague have developed a workable overhead contact system, leading to the streetcar as we knew it in OTL, at about the same time (1888)?
* Would cable systems survive to this day outside San Francisco (where they were retained for hill climbing and tourist attractions)? (Bear in mind that there were cable systems in nearly every major US city outside the south at one point, with the exceptions of Boston, Buffalo and Minneapolis that I can recall offhand.)