1. A method of providing content via a computer network, comprising: receiving, by a data processing system via a sensor of a computing device, location information of the computing device; determining, by the data processing system based on the location information, a geographic location of the computing device; determining non-geographic semantic characteristics of a geographic area that is larger than, but includes, the geographic location of the computing device, based on at least one quantitative value of a population metric, a topographical metric, or a climate metric for the geographic area; prior to a request for content by the computing device and in response to determining the geographic location of the computing device, receiving, by the data processing system and from a database, a location feature index comprising a plurality of data structures with data pertaining to the geographic area that includes the geographic location of the computing device; searching the location feature index to identify a first data structure representing one or more of the non-geographic semantic characteristics of the geographic area; identifying, in the location feature index, a second data structure mapped to the first data structure, with the second data structure representing a particular keyword, wherein identification of the second data structure from the first data structure in the location feature index provides for keyword identification for the geographic area that is distinct from content of the request; selecting, by the data processing system, based on the identified second data structure representing the particular keyword, a candidate content item for display on the computing device, the candidate content item satisfying selection criteria indicating that the candidate content item is to be selected for the particular keyword; and providing, in response to the request for content by the computing device, the selected candidate content item to the computing device while the computing device is at the geographic location.