Portland-Vancouver Metropolitan Study

The boundaries for urban development and principal transportation were derived from a variety of sources ranging in scale and resolution. Sources included historical topographic maps, land use and land cover maps, digital line graphs for transportation, aerial photography, and Landsat Multispectral Scanner and Thematic Mapper data. The compilation of urban development was accomplished by a combination of manual photo-interpretation and automated spectral classification techniques. The type of source materials available determined the actual procedures that were used. A geographic information system (GIS) was used to assemble and integrate the data.

Topographic Maps

USGS's rich 100 year archive of topographic maps is a major map source. Other map sources include the Defense Mapping Agency, formerly the Army Map Service, and the U.S. Coast and Geodetic Survey. The most useful maps vary in scale from approximately 1:12,000 to 1:158,000.

Historical maps (1914, 1947, 1985) of Oregon City, OR (1.01 Mbytes)
1914 Map of Oregon City (678 Kbytes)

Landsat Data

Landsat satellite data provided the most continuous and uniform data available at the regional scale. The Landsat MSS, with a 57- by 79-square meter pixel spatial resolution, and the TM scanner, with a much better 28.5-square meter resolution, provided the data for continuous monitoring of development starting in 1972.

Portland and Vancouver in 1986 (500 Kbytes)
Eugene in 1986 (580 Kbytes)

Digital Line Graphs

The 1:100,000-scale digital line graph (DLG) of transportation features were used to determine the extent of the urban areas in the 1980's.

DLG for Salem

Digital Land Use and Land Cover Data

The USGS GIRAS land use and land cover (LULC) data provided a digital source of LULC maps and associated overlays at 1:250,000 scale.

LULC Data for Portland and Vancouver

Digital Orthophoto Quadrangles

The USGS produced DOQ data product promises to provide a valuable source of high resolution, rectified photography for use in land cover mapping. The data is just becoming available for selected areas and will be updated on a five year cycle. Future updates of the urban delineations can be derived from these high resolution data sources.