This is a mathematically generated grid in which each polygon represents one quarter of the already quartered 225 second (or 3 3/4 minute) data resource, or a quarter-quarter of...

Mathematically generated grid representing USGS 7 1/2 Minute Quadrangle Map outlines. Quadrangle names and standard identifiers are included with the data set.

This is a mathematically generated grid in which each polygon represents one quarter of a standard USGS 7 1/2 minute quadrangle. The result is a 3 3/4 minute quadrangle layer...

USGS 1:100,000 scale Quadrangle Map Index derived from the larger scale double precision 7 1/2 Minute Quadrangle Index.

USGS 1:250,000 scale Quadrangle Map Index with quadrangle name and standard identifiers.