Quadrangle (geography)

A quadrangle is defined by north and south boundaries of constant latitude (which are not great circles so are curved), and by east and west boundaries of constant longitude.

[1] A 7.5 minute quadrangle map covers an area of 49 to 70 square miles (130 to 180 km2).

[2] Both map series were produced via photogrammetric analysis of aerial photography using stereoplotters supplemented by field surveys.

Beginning in 2009, the USGS made available digital versions of 7.5 minute quadrangle maps based on GIS data that use the NAD83 datum, which is typically within one meter of WGS84, or within the uncertainty of most GPS coordinate measurements.

The USGS also produces quarter quadrangle (QQ) maps of areas 3.75 minutes square.

New York (Essex County) Mt. Marcy : an 1892 USGS quadrangle map (or topographic sheet ) of the Mount Marcy area of the Adirondacks in New York State from the first decades of the United States Geological Survey.