Using our historical map archives and Landsat Thematic Mapper data, NMD is building a temporal data set of urban growth in the Seattle-Tacoma area on a 10-year time interval between 1950 and 2000. Examples of the data for 1970 and 1990 are shown below, with gray depicting urbanized areas, and brown signifying industrial areas. This technique has been applied in several other urban areas as part of NMD Urban Growth studies.