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USGS 1:24000 (7 1/2 Minute) Quadrangle Index
Mathematically generated grid representing USGS 7 1/2 Minute Quadrangle Map outlines. Quadrangle names and standard identifiers are included with the data set. -
USGS 1:100000 (1 by 1/2 Degree) Quadrangle Index
USGS 1:100,000 scale Quadrangle Map Index derived from the larger scale double precision 7 1/2 Minute Quadrangle Index. -
USGS 1:250000 (2 by 1 Degree) Quadrangle Index
USGS 1:250,000 scale Quadrangle Map Index with quadrangle name and standard identifiers.
