In order to deal with semantic heterogeneity and achieve semantic interoperability between heterogeneous applications, it is necessary to formalize geographic knowledge. The present paper introduces a method to formalize and integrate different geographic categorizations. The method is based on the mathematical theory of Concept Lattices. These rich structures are used for managing multidimensional geographic categories and their overlapping relationships. The applicability of the method is tested on the problem of integrating different land cover/land use categorizations.