![]() ![]() The size of this difference for a particular map depends on the projection and the map location relative to the projection origin. The difference between true north and grid north is an inherent effect of transforming the earth's spherical surface to a plane surface. Historical topographic maps might relate grid north to other grid systems. All US Topo maps have a 1,000-meter UTM grid included on the map the angle at which this grid meets the map projection line visually shows the difference between true and grid north. On current US Topo maps, the projection is Transverse Mercator and the plane grid is Universal Transverse Mercator (UTM). Grid north (GN) is the direction of a plane grid system, usually the grid associated with the map projection. Political maps, physical maps, road maps. ![]() Reference maps show the location of geographic boundaries, physical features of Earth, or cultural features such as places, cities, and roads. Most of these maps can be placed into one of two groups: 1) reference maps and, 2) thematic maps. Magnetic declination values shown on current maps are obtained from NOAA's National Geophysical Data Center. Millions of unique maps are in use throughout the world. The direction of magnetic north varies over time and with the position on the earth's surface, so magnetic declination values on old maps might no longer be accurate. US Topo maps integrate an orthoimage, which is a significant enhancement to the original USGS topographic maps regarding currency and completeness. Forest Service, and the National Park Service. From the PAD-US map you can identify protected areas managed by various federal agencies such as the Bureau of Land Management, the U.S. National, state, regional, and local organizations all manage protected lands. Magnetic north (MN) shows the direction a magnetic compass would point at the time the map was published. Explore the different types of public lands in the United States. The star symbol in the diagram indicates true north. All longitude lines converge to points at the north and south poles. True north, also called geodetic north or geographic north, is the direction of the line of longitude that bisects the quadrangle. Star is True north, GN is Grid north, MN is Magnetic north. Example of north arrows from US Topo map. ![]()
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