Why are USGS historical topographic maps referenced to outdated datums?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, coordinates obtained using NAD83 could be hundreds of meters away from coordinates obtained using NAD27. 

  • The World Geodetic System of 1984 (WGS84) is identical to NAD83 for most practical purposes within the United States. WGS84 is the default datum setting for almost all GPS devices. But most USGS topographic maps published through 2006 use NAD27. This conflict in datums can cause big problems for the uninformed GPS user.

The primary purpose of the Historical Topographic Map Collection (HTMC) project is to make older USGS topographic quadrangle maps--those published between 1884 and 2006--available to the public. Scans of those maps are referenced to the spatial reference system of the original published map. 

 These maps have many uses for historical analysis but the USGS does not endorse using them for any current operational purpose.

Learn more: 

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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. The best known USGS maps are the 1:24,000-scale topographic maps, also known as 7.5-minute quadrangles. Download all dates and scales of USGS topographic maps free of charge from the following applications or order paper copies of all...

Where can I find indexes of USGS topographic maps?

View map indices on these interactive maps (you must zoom in to see the index lines and map names) : Map Locator on the USGS Store - Click the icon on the left that looks like two pieces of paper and select “1:24,000”. TopoView - Click on any of the round map scale indicators on the right side of the map. The National Map Viewer - Click on the...

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...

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,...

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...

Are there metadata Files for USGS topographic maps?

Yes. GeoPDF files for both Historical topographic maps (produced 1884-2006) and US Topo maps (produced 2009-present) 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 (a US Topo Map...

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.

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...
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Date published: July 19, 2017

Historical Maps at Your Fingertips

Earlier this month, the USGS launched “TopoView 2.1”, an enhancement to the current popular TopoView mapping service that lets users discover, interact, and download historical USGS topographic maps scans.

Date published: July 5, 2017

Finding Yourself Outdoors

Updated USGS digital topographic maps feature more trails and other recreation points of interest

Filter Total Items: 5
December 18, 2017

Lesson 9a: Accessing US Topo and Historical USGS Topographic Maps

In this lesson, we will discuss the USGS Store and how it can be used to access the US Topo and historical USGS Topographic maps. Specifically, this lesson will talk about the USGS Store, both where it’s accessed and what’s available at the store, as well as how you can locate and download free topographic maps through the store. 
 

Scanned USGS historical map of the Yorktown, Virginia area, circa 1907
December 31, 1907

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

1907 map - "Scanned USGS historical map of the Yorktown, Virginia area, circa 1907. Source: Historical Topographic Map Collection."

Historical Topographic Map Collection: Denver, CO 1890

Historical Topographic Map Collection: Denver, CO 1890

Historical Topographic Map Collection: Denver, CO 1890

Browse Image of 1890 Historical Topographic Map

Browse Image of 1890 Historical Topographic Map

Browse Image of 1890 historical topographic map for the Newburyport quadrangle, a digital map in the USGS Historical Topographic Map Collection

This is a USGS Ed Resource thumbnail.
April 25, 2019

Datum Shifts

Attribution: Science Support