Why are USGS topographic maps called “quadrangles”?
In the making of topographic maps, the USGS subdivides the United States by using Latitude and Longitude lines to form the boundaries of four-sided figures called “quadrangles”. The maps are often referred to as quadrangle maps (or quad maps). Different sizes of quadrangles have been used over time, for example the 30-minute quadrangle (30 minutes of latitude or longitude on each side) and the 15...