Significant Topographic Changes in the United States
Quadrangle Base Maps
Many resource managers and geospatial data users are familiar with the USGS 7.5-minute quadrangle map series. Also, much of the geospatial data managed by the USGS was originally produced in tiles corresponding to the 7.5-minute maps. The topographic map quadrangles are still commonly used as base maps for outlining data collection strategies and defining project boundaries. Thus, it is useful to characterize the extent of the topographic change inventory in terms of the footprints of the 7.5-minute map series.
The figure below shows the 7.5-minute quadrangles within the conterminous United States that contain topographic change polygons.
Summary Statistics and Rankings:
Top Ranked Quadrangles (by Percentage) Containing Topographic Change Polygons