USGS Map Indices Overlay Map Service from The National Map
The USGS Map Indices service from The National Map (TNM) consists of 1x1 Degree, 30x60 Minute (100K), 15 Minute (63K), 7.5 Minute (24K), and 3.75 Minute grid polygons used in The National Map viewer for reference and to download data. At 1:24,000-scale (24K), the standard map size is 7.5 minutes of latitude by 7.5 …