1. A method comprising: indexing, by one or more processors in one or more computer devices, a plurality of documents in a document index, where indexing each document, of the plurality of documents, includes: extracting, from each document, a geographic location associated with the document, identifying a particular geographic area associated with the geographic location, determining a plurality of geographic areas within a first range of the particular geographic area associated with the document, where the plurality of geographic areas are not associated with the document, and adding a plurality of references to the document to the document index, wherein the plurality of added references respectively reference the document by the particular geographic area and the plurality of geographic areas; receiving, by one or more processors in the one or more computer devices, a search query that includes one or more geographically descriptive terms; determining a search region based on the one or more geographically descriptive terms included in the search query; and identifying one or more documents in the document index based on the search region.