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...
Maps and Mapping
How do I find, download, or order topographic maps?
What types of elevation datasets are available, what formats do they come in, and where can I download them?
What is a Digital Orthophoto Quadrangle (DOQ) or an orthoimage?
The USGS provides the mapping and digital geospatial foundation for the Nation.