The complexity of binary maps that is provided by the areal arrangement of colors is considered, and measured using information theory. In addition, information theory provides other measures that have an interpretation in a map context. One of these, redundancy, is examined and found to bear a striking empirical relationship to a spatial autocorrelation statistic. It is argued that spatial autocorrelation is, conceptual1 y as well as empirically, the two-dimensional equivalent of redundancy. It too measures the extent to which the occurrence of an event (color) in an areal unit constrains, or makes more probable, the occurrence of an event in a neighboring areal unit.The observation that maps are devices for the communication of information has gained wide currency in the cartographic literature [ 19, 231. As natural languages fulfill the same purpose, it is reasonable to argue that maps may be conceived, in a general sense, as output from languages. Given such a conceptualization it seems worthwhile to explore the possibilities of using the ideas and methods of linguistics in map analysis. In this paper, information theory is used to examine two syntactic or grammatical aspects of maps, complexity and redundancy.Harvey asserts that map syntax embraces "the internal structure of the map statements and its basic form as an abstract calculus" [15, pp. 373-741. In natural language it is concerned, broadly speaking, with the way in which elements of the language are put together, that is, with the rules of sentence construction. Extending this into two dimensions, it can be argued that map syntax involves notions of spatial association, periodicity [23, pp. 5-61, and the search for the rules that generate a map pattern. INFORMATION CONTENT AND REDUNDANCY IN ONE AND Two DIMENSIONS Information theory [27] is becoming well known in the geographic literature [3, 171. It can be used to measure the uncertainty or "informa-*This paper is based on my Master's thesis, "Complexity and Redundancy in Choropleth Maps," The Pennsylvania State University, 1974. I would like to thank Professor Peter Gould and Dr. Conrad Strack for their helpful advice and encouragement.Anthony C. Gatrell is lecturer in geography, Uiiicersity of Salford.