A survey base station is established using a RTK-GPS receiver with mobile units to collect data points in and around the crater. Information will be used to monitor surface changes, deformation, erosion and aggradation inside the crater. This type of technology is precise to the centimeter. View to the south, toward Crater Glacier and the lava domes.
What is the State Plane Coordinate System? Can GPS provide coordinates in these values?
The State Plane Coordinate System (SPCS), which is only used in the United States, is a plane coordinate system (north-south and east-west lines are perpendicular) in which each individual state has between one to six zones, depending on the state's size and shape. This coordinate system’s high level of accuracy is achieved through the use of relatively small zones.
The State Plane Coordinate System’s 120 different zones generally follow county boundaries (except in Alaska). Larger states are divided into multiple zones, such as the “Colorado North Zone.” States with a long north-south axis (such as Idaho and Illinois) are usually mapped using a Transverse Mercator projection, while states with a long east-west axis (such as Washington and Pennsylvania) are usually mapped using a Lambert Conformal projection. In either case, the projection's central meridian is generally run down the approximate center of the zone.
A Cartesian coordinate system is created for each zone by establishing an origin some distance (usually 2,000,000 feet) to the west of the zone's central meridian and some distance to the south of the zone's southernmost point. This ensures that all coordinates within the zone will be positive. The X-axis running through this origin runs east-west, and the Y-axis runs north-south. Distances from the origin are generally measured in feet, but sometimes are in meters. X distances are typically called eastings (because they measure distances east of the origin) and Y distances are typically called northings (because they measure distances north of the origin).
When the State Plane Coordinate System is shown on a USGS topographic map, the zone is given in the credit legend in the map’s collar. Grid ticks are shown along the map projection line and coordinate values are annotated at one or more corners. However, on most USGS 7.5-minute Historical topographic maps produced 1947-1995, the grid is tied to the outdated North American Datum of 1927 (NAD27), so coordinates on the map might differ by hundreds of meters from coordinates obtained by modern instruments using newer datums.
With the advent of the North American Datum of 1983 (NAD83)--which is virtually identical to the World Geodetic System of 1984 (WGS84) within the United States--State Plane coordinates shifted with it. Offset from the different datums is indicated by a dashed cross in each corner of some topographic maps.
US Topo maps produced 2010-2016 are annotated with NAD83 State Plane Coordinate values, but those ticks and annotations were dropped from US Topo maps in 2017.
Most Geographic Information Systems (GIS) can display SPCS values and grids, and some consumer GPS devices and apps also implement SPCS. Currently, SPCS is mostly used for land surveying and specialized local mapping.
Related Content
How are UTM coordinates measured on USGS topographic maps?
The UTM ( Universal Transverse Mercator ) coordinate system divides the world into sixty north-south zones, each 6 degrees of longitude wide. UTM zones are numbered consecutively beginning with Zone 1, which includes the westernmost point of Alaska, and progress eastward to Zone 19, which includes Maine. If UTM ticks are shown on a USGS topographic map, the zone is indicated in the credit legend...
Why are the NAD 83 position values so far from the NAD 27 values? Were the old coordinates wrong?
The old coordinates were not wrong, just different. Positions obtained using the North American Datums of 1927 ( NAD 27 ) and 1983 ( NAD 83 ) are based on different earth shapes--or ellipsoids--and used the best technology available at the time. Mathematically, NAD 83 is a stronger datum because all previously existing horizontal stations and newer GPS surveyed stations were adjusted...
How large is the North American Datum of 1927 (NAD 27) to NAD 83 shift?
Within the conterminous 48 states, the North American Datum of 1927 (NAD 27) to the North American Datum of 1983 (NAD 83) shift of the latitude/longitude graticule (lines showing parallels of latitude and meridians of longitude for the earth) is in the range of 10-100 ground meters. Changes to UTM values are generally larger, around 200 meters, and changes for other coordinate systems are...
Why are USGS historical topographic maps referenced to outdated datums?
Many different horizontal reference datums exist, but in the United States only three datums are commonly used: The North American Datum of 1927 ( NAD27 ) uses a starting point at a base station in Meades Ranch, Kansas and the Clarke Ellipsoid to calculate the shape of the Earth. The North American Datum of 1983 ( NAD83 ) was developed when satellites enabled a better model. Depending on one’s...
How do I find, download, or order topographic maps?
The U.S. Geological Survey (USGS) has been the primary civilian mapping agency of the United States since 1879. Some of the most well-known USGS maps are the 1:24,000-scale topographic maps, also called 7.5-minute quadrangles . In 2009, the USGS transitioned from our hand scribed historical topographic maps to US Topos , which are computer-generated on a regular schedule using national databases...
Are there metadata files for USGS topographic maps?
GeoPDF files for both Historical Topographic maps (produced 1884-2006), U S Topo maps (produced 2009-present), and OnDemand Topo maps come with an XML metadata file attached to each GeoPDF file. To access the metadata file, download the GeoPDF file, open it in Acrobat Reader, click on the paperclip icon, then select a file from the list that appears (US Topo maps also come with a Map Symbols...
When was the 1:24,000-scale topographic map series for the United States and its territories completed?
The U.S. Geological Survey (USGS) was created in 1879 and published it’s first topographic map in 1882. Systematic topographic mapping was authorized by Congress in 1884. Although 1:24,000-scale topographic maps were produced by the USGS as early as 1904, a formal program to provide primary topographic map coverage at that scale for the entire conterminous United States did not begin until 1947...
How do US Topo maps differ from historical USGS topographic maps?
Historically, USGS topographic maps were made using data from primary sources including direct field observations. Those maps were compiled, drawn, and edited by hand. By today's standards, those traditional methods are very expensive and time-consuming, and the USGS no longer has funding to make maps that way. A new USGS topographic map series was launched in 2009 and branded " US Topo ." Though...
Precise surveying of Mount St. Helens crater with RTK-GPS technology.
A survey base station is established using a RTK-GPS receiver with mobile units to collect data points in and around the crater. Information will be used to monitor surface changes, deformation, erosion and aggradation inside the crater. This type of technology is precise to the centimeter. View to the south, toward Crater Glacier and the lava domes.
Related Content
- FAQ
How are UTM coordinates measured on USGS topographic maps?
The UTM ( Universal Transverse Mercator ) coordinate system divides the world into sixty north-south zones, each 6 degrees of longitude wide. UTM zones are numbered consecutively beginning with Zone 1, which includes the westernmost point of Alaska, and progress eastward to Zone 19, which includes Maine. If UTM ticks are shown on a USGS topographic map, the zone is indicated in the credit legend...
Why are the NAD 83 position values so far from the NAD 27 values? Were the old coordinates wrong?
The old coordinates were not wrong, just different. Positions obtained using the North American Datums of 1927 ( NAD 27 ) and 1983 ( NAD 83 ) are based on different earth shapes--or ellipsoids--and used the best technology available at the time. Mathematically, NAD 83 is a stronger datum because all previously existing horizontal stations and newer GPS surveyed stations were adjusted...
How large is the North American Datum of 1927 (NAD 27) to NAD 83 shift?
Within the conterminous 48 states, the North American Datum of 1927 (NAD 27) to the North American Datum of 1983 (NAD 83) shift of the latitude/longitude graticule (lines showing parallels of latitude and meridians of longitude for the earth) is in the range of 10-100 ground meters. Changes to UTM values are generally larger, around 200 meters, and changes for other coordinate systems are...
Why are USGS historical topographic maps referenced to outdated datums?
Many different horizontal reference datums exist, but in the United States only three datums are commonly used: The North American Datum of 1927 ( NAD27 ) uses a starting point at a base station in Meades Ranch, Kansas and the Clarke Ellipsoid to calculate the shape of the Earth. The North American Datum of 1983 ( NAD83 ) was developed when satellites enabled a better model. Depending on one’s...
How do I find, download, or order topographic maps?
The U.S. Geological Survey (USGS) has been the primary civilian mapping agency of the United States since 1879. Some of the most well-known USGS maps are the 1:24,000-scale topographic maps, also called 7.5-minute quadrangles . In 2009, the USGS transitioned from our hand scribed historical topographic maps to US Topos , which are computer-generated on a regular schedule using national databases...
Are there metadata files for USGS topographic maps?
GeoPDF files for both Historical Topographic maps (produced 1884-2006), U S Topo maps (produced 2009-present), and OnDemand Topo maps come with an XML metadata file attached to each GeoPDF file. To access the metadata file, download the GeoPDF file, open it in Acrobat Reader, click on the paperclip icon, then select a file from the list that appears (US Topo maps also come with a Map Symbols...
When was the 1:24,000-scale topographic map series for the United States and its territories completed?
The U.S. Geological Survey (USGS) was created in 1879 and published it’s first topographic map in 1882. Systematic topographic mapping was authorized by Congress in 1884. Although 1:24,000-scale topographic maps were produced by the USGS as early as 1904, a formal program to provide primary topographic map coverage at that scale for the entire conterminous United States did not begin until 1947...
How do US Topo maps differ from historical USGS topographic maps?
Historically, USGS topographic maps were made using data from primary sources including direct field observations. Those maps were compiled, drawn, and edited by hand. By today's standards, those traditional methods are very expensive and time-consuming, and the USGS no longer has funding to make maps that way. A new USGS topographic map series was launched in 2009 and branded " US Topo ." Though...
- Multimedia
Precise surveying of Mount St. Helens crater with RTK-GPS technology.
A survey base station is established using a RTK-GPS receiver with mobile units to collect data points in and around the crater. Information will be used to monitor surface changes, deformation, erosion and aggradation inside the crater. This type of technology is precise to the centimeter. View to the south, toward Crater Glacier and the lava domes.
A survey base station is established using a RTK-GPS receiver with mobile units to collect data points in and around the crater. Information will be used to monitor surface changes, deformation, erosion and aggradation inside the crater. This type of technology is precise to the centimeter. View to the south, toward Crater Glacier and the lava domes.
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