BLM REA CYR 2013 Community Footprints in the Central Yukon study area

The community footprints for the CYR REA were produced by digitally tracing the built areas from satellite imagery. This was done to represent the actual community footprints more accurately than would have been possible from the U.S. Census Bureau’s Topologically Integrated Geographic Encoding and Referencing (TIGER) files. TIGER files are geospatial files with information on several political and administrative units. These shapefiles include polygon boundaries of geographic areas and features, linear features including roads and hydrography, and point features. The communities in Alaska were released as a polygon shapefile, with each community’s boundary identified. However, there were two major concerns with this file: i. Community boundary polygons represent the legal boundaries and not the actual developed areas. The actual developed area for each community in the region is much smaller than its legal boundary. Moreover in many instances, boundaries as identified in TIGER files are not legal boundaries recognized under state law. Therefore, these polygon boundaries are not accurate representations of existing communities, and over-represent the actual community footprints. ii. Many of the maps produced for this project show community-level social and demographic information. For better representation in such maps, a point file was used instead of a polygon file to identify communities. Generation of a point file from a polygon file is done by locating the point at the center of gravity of the polygon. Given the large polygons in the community TIGER file, centers of gravity are often well outside the actual community footprints. As a result, Census TIGER files were not used in identifying community footprints. Instead, each community’s footprint was digitized from satellite imagery. A majority of the communities in the CYR REA study area are small and their footprints are concentrated in small areas with some activities scattered around each community's central location. Population in each community is often low and activity beyond identified footprint boundaries is limited to subsistence-use and inter-community trails.