This raster layer shows the areas of Ansan-si, Kyŏnggi-do, Korea which were developed between 1990 and 2000. Categories of new development represented in these data include: infill, extension and leapfrog. Infill represents development within all the open spaces in the urban footprint of the earlier period excluding exterior open space. Extension represents development in contiguous clusters that contained exterior open space in the earlier period and that were not infUnited States Leapfrog represents development entirely outside the exterior open space of the earlier period. These data are part of the Atlas of Urban Expansion.The Atlas of Urban Expansion provides the geographic and quantitative dimensions of urban expansion and its key attributes in cities the world over. The data and images are available for free downloading, for scholars, public officials, planners, those engaged in international development, and concerned citizens. The global empirical evidence presented here is critical for an intelligent discussion of plans and policies to manage urban expansion everywhere. This resource provides both the conceptual framework and, for the first time, the basic empirical data and quantitative dimensions of past, present, and future urban expansion in cities around the world that are necessary for making minimal preparations for the massive urban growth expected in the coming decades.