1. A computer-implemented method for automatically generating a map, the method comprising: determining, by a computer, a frequency with which each of a plurality of city names occurs in a corpus of documents; associating, by the computer, each city name with one of a plurality of city categories according to the determined frequency of the city name in the corpus; and generating, by the computer a digital map including the city names, wherein an appearance of each city name on the map is determined by the category with which it is associated.