8. A system comprising: a data processing apparatus; and a computer storage medium encoded with a computer program, the program comprising instructions that when executed by the data processing apparatus cause the data processing apparatus to perform operations comprising: for each of a plurality of queries stored in search log data, each of the queries comprising one or more terms, and each of the queries having one or more occurrences of the same one or more terms in the search log data: determining, for each of a plurality of catchment areas, catchment area matches for the query based on an origin location of each occurrence of the query and a location term of each occurrence of the query; determining a catchment area type for the query from the location term of the query; determining, for each of a plurality of catchment areas, each catchment area belonging to one of a plurality of catchment area types, a number of catchment area matches for the catchment area for the query, each catchment area match being an occurrence of the query having a location term that specifies the catchment area of the catchment area type in which the origin location for the occurrence of the query is located; and selecting one of the catchment areas as a selected catchment area for the query based on the number of catchment area matches.
8. A system comprising: a data processing apparatus; and a computer storage medium encoded with a computer program, the program comprising instructions that when executed by the data processing apparatus cause the data processing apparatus to perform operations comprising: for each of a plurality of queries stored in search log data, each of the queries comprising one or more terms, and each of the queries having one or more occurrences of the same one or more terms in the search log data: determining, for each of a plurality of catchment areas, catchment area matches for the query based on an origin location of each occurrence of the query and a location term of each occurrence of the query; determining a catchment area type for the query from the location term of the query; determining, for each of a plurality of catchment areas, each catchment area belonging to one of a plurality of catchment area types, a number of catchment area matches for the catchment area for the query, each catchment area match being an occurrence of the query having a location term that specifies the catchment area of the catchment area type in which the origin location for the occurrence of the query is located; and selecting one of the catchment areas as a selected catchment area for the query based on the number of catchment area matches. 11. The system of claim 8 , wherein: the catchment areas include a city catchment area type, a metro catchment area type, and a state catchment area type; and determining the catchment area matches for each catchment are comprises capping a number of matches for each catchment area in proportion to the size of the catchment area type.