ties, and several special-purpose management districts, is responsible for land use and transportation planning in the region. Because Portland set an urban growth boundary in 1979 that limits the physical expansion of the city, land use planning is a major policy focus in the region, and spatial data assume a critical role in policy discussions.

Metro maintains its spatial data in a regional GIS called the Regional Land Information System (RLIS), which contains information on land records and the built environment. Aerial photography has been used for about 10 years to inventory land use and natural resources within RLIS (Figure 2.3). This information has been supplemented with limited data on land cover from federal sources, principally FEMA and USGS. Satellite remote sensing data were first added to the RLIS in 1998, when Metro used Landsat imagery to obtain data on land cover in the region (Figure 2.4). The goal was to identify land that served as habitat for wildlife. Metro officials told workshop participants that their current goal is to

FIGURE 2.3 Annual vacant lots inventory of undeveloped land. The technique to produce the inventory uses visual interpretation of aerial photography to measure the land supply. SOURCE: Metro Data Resource Center.