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Why do all of the coordinates (latitude and longitude) in the Geographic Names Information System seem incorrect?

Coordinates that seem to be incorrect in the Geographic Names Information System might just be projected on a different datum from the datum used on your map or your positioning system (GPS).

 Most USGS maps published approximately 1940-1995 are projected on the North American Datum of 1927 (NAD27). Later maps are projected on the North American Datum of 1983 (NAD83). The "datum shift" changes the coordinate values of fixed ground points.

The shift is different for different coordinate systems. UTM, State Plane, and geographic (latitude/longitude) values change by different amounts. A change in UTM values of roughly 200 meters in the north-south direction (the exact value varies with location) indicates a NAD27-NAD83 datum shift. Changes in State Plane Coordinate System (SPCS) values can be much larger, and can vary between states.

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Image: USGS Topographers at Work

How large is the North American Datum (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...

link

How large is the North American Datum (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...

Learn More
link
longitude convergence

What location coordinates (datum) does the Geographic Names Information System use?

All coordinates in the Geographic Names Information System database are in the North American Datum of 1983 (NAD 83). They were converted from the North American Datum of 1927 (NAD 27) in September 2005.

link

What location coordinates (datum) does the Geographic Names Information System use?

All coordinates in the Geographic Names Information System database are in the North American Datum of 1983 (NAD 83). They were converted from the North American Datum of 1927 (NAD 27) in September 2005.

Learn More
link
Scanned USGS historical map of the Yorktown, Virginia area, circa 1907

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 location...

link

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 location...

Learn More
link
Map of the lower 48 states with vertical lines superimposed to indicate ten UTM zones numbered left to right from 10 to 19.

What does the term UTM mean? Is UTM better or more accurate than latitude/longitude?

UTM is the acronym for Universal Transverse Mercator, a plane coordinate grid system named for the map projection on which it is based (Transverse Mercator). The UTM system consists of 60 zones, each 6-degrees of longitude in width. The zones are numbered 1-60, beginning at 180-degrees longitude and increasing to the east. The military uses their own implementation of the UTM system, called the...

link

What does the term UTM mean? Is UTM better or more accurate than latitude/longitude?

UTM is the acronym for Universal Transverse Mercator, a plane coordinate grid system named for the map projection on which it is based (Transverse Mercator). The UTM system consists of 60 zones, each 6-degrees of longitude in width. The zones are numbered 1-60, beginning at 180-degrees longitude and increasing to the east. The military uses their own implementation of the UTM system, called the...

Learn More
link
Image shows a scientific instrument on the slopes of Mount St Helens

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...

link

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...

Learn More
link
GIS data layers visualization

How can I acquire or download Geographic Names Information System (GNIS) data?

Download Geographic Names Information System (GNIS) data using the U.S. Board on Geographic Names website. Query the database for official geographic feature names, their location attributes, variant names, and other data. Display, print, and download up to 2,000 records from a query.GNIS data can also be downloaded via The National Map Downloader. Define an area of interest on the map, then put a...

link

How can I acquire or download Geographic Names Information System (GNIS) data?

Download Geographic Names Information System (GNIS) data using the U.S. Board on Geographic Names website. Query the database for official geographic feature names, their location attributes, variant names, and other data. Display, print, and download up to 2,000 records from a query.GNIS data can also be downloaded via The National Map Downloader. Define an area of interest on the map, then put a...

Learn More
link
Image: Rocky Mountain National Park

What is the Geographic Names Information System (GNIS)?

The Geographic Names Information System (GNIS) was developed by the U.S.Geological Survey (USGS) in cooperation with the U.S. Board on Geographic Names (BGN), which maintains cooperative working relationships with state names authorities to standardize geographic names. GNIS contains information about the official names for places, features, and areas in the 50 states, the District of Columbia...

link

What is the Geographic Names Information System (GNIS)?

The Geographic Names Information System (GNIS) was developed by the U.S.Geological Survey (USGS) in cooperation with the U.S. Board on Geographic Names (BGN), which maintains cooperative working relationships with state names authorities to standardize geographic names. GNIS contains information about the official names for places, features, and areas in the 50 states, the District of Columbia...

Learn More
Everglades National Park sign
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Finding Your Way with Map and Compass

A topographic map tells you where things are and how to get to them, whether you're hiking, biking, hunting, fishing, or just interested in the world around you. These maps describe the shape of the land. They define and locate natural and manmade features like woodlands, waterways, important buildings, and bridges. They show the distance between any two places, and they also show the direction fr

Related Content

  • FAQ
    link
    Image: USGS Topographers at Work

    How large is the North American Datum (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...

    link

    How large is the North American Datum (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...

    Learn More
    link
    longitude convergence

    What location coordinates (datum) does the Geographic Names Information System use?

    All coordinates in the Geographic Names Information System database are in the North American Datum of 1983 (NAD 83). They were converted from the North American Datum of 1927 (NAD 27) in September 2005.

    link

    What location coordinates (datum) does the Geographic Names Information System use?

    All coordinates in the Geographic Names Information System database are in the North American Datum of 1983 (NAD 83). They were converted from the North American Datum of 1927 (NAD 27) in September 2005.

    Learn More
    link
    Scanned USGS historical map of the Yorktown, Virginia area, circa 1907

    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 location...

    link

    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 location...

    Learn More
    link
    Map of the lower 48 states with vertical lines superimposed to indicate ten UTM zones numbered left to right from 10 to 19.

    What does the term UTM mean? Is UTM better or more accurate than latitude/longitude?

    UTM is the acronym for Universal Transverse Mercator, a plane coordinate grid system named for the map projection on which it is based (Transverse Mercator). The UTM system consists of 60 zones, each 6-degrees of longitude in width. The zones are numbered 1-60, beginning at 180-degrees longitude and increasing to the east. The military uses their own implementation of the UTM system, called the...

    link

    What does the term UTM mean? Is UTM better or more accurate than latitude/longitude?

    UTM is the acronym for Universal Transverse Mercator, a plane coordinate grid system named for the map projection on which it is based (Transverse Mercator). The UTM system consists of 60 zones, each 6-degrees of longitude in width. The zones are numbered 1-60, beginning at 180-degrees longitude and increasing to the east. The military uses their own implementation of the UTM system, called the...

    Learn More
    link
    Image shows a scientific instrument on the slopes of Mount St Helens

    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...

    link

    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...

    Learn More
    link
    GIS data layers visualization

    How can I acquire or download Geographic Names Information System (GNIS) data?

    Download Geographic Names Information System (GNIS) data using the U.S. Board on Geographic Names website. Query the database for official geographic feature names, their location attributes, variant names, and other data. Display, print, and download up to 2,000 records from a query.GNIS data can also be downloaded via The National Map Downloader. Define an area of interest on the map, then put a...

    link

    How can I acquire or download Geographic Names Information System (GNIS) data?

    Download Geographic Names Information System (GNIS) data using the U.S. Board on Geographic Names website. Query the database for official geographic feature names, their location attributes, variant names, and other data. Display, print, and download up to 2,000 records from a query.GNIS data can also be downloaded via The National Map Downloader. Define an area of interest on the map, then put a...

    Learn More
    link
    Image: Rocky Mountain National Park

    What is the Geographic Names Information System (GNIS)?

    The Geographic Names Information System (GNIS) was developed by the U.S.Geological Survey (USGS) in cooperation with the U.S. Board on Geographic Names (BGN), which maintains cooperative working relationships with state names authorities to standardize geographic names. GNIS contains information about the official names for places, features, and areas in the 50 states, the District of Columbia...

    link

    What is the Geographic Names Information System (GNIS)?

    The Geographic Names Information System (GNIS) was developed by the U.S.Geological Survey (USGS) in cooperation with the U.S. Board on Geographic Names (BGN), which maintains cooperative working relationships with state names authorities to standardize geographic names. GNIS contains information about the official names for places, features, and areas in the 50 states, the District of Columbia...

    Learn More
  • Multimedia
    Everglades National Park sign
    link
  • Publications

    Finding Your Way with Map and Compass

    A topographic map tells you where things are and how to get to them, whether you're hiking, biking, hunting, fishing, or just interested in the world around you. These maps describe the shape of the land. They define and locate natural and manmade features like woodlands, waterways, important buildings, and bridges. They show the distance between any two places, and they also show the direction fr