Map Indices

USGS map indices containing cell grids of 1x2 degree, 1x1 degree, 30x60 minute, 15x15 minute, 7.5x7.5 minute (or Quad), and 3.75x3.75 minute (or Quarter Quad) are included in the .zip file.
USGS map indices are distributed by State in either File Geodatabase 9.3.1 or 10.1 format, or Shapefile.