24. The method of claim 16 in which each document in the corpus is written in the same language.
16. A method for labeling cities on a digital map, the method comprising: determining, by a computer, a priority score for each of a plurality of cities, the priority score determined according to a frequency with which the city appears in a corpus of documents; categorizing each city, by the computer, according to its determined priority score; and rendering, by the computer, a digital map including at least some of the cities, each included city having a label with an appearance determined at least in part by the category to which the city belongs.