Mapping, Remote Sensing, and Geospatial Data

How much distance does a degree, minute, and second cover on your maps?

The distances vary. A degree, minute, or second of latitude remains fairly constant from the equator to the poles; however a degree, minute, or second of longitude can vary greatly as one approaches the poles (because of the convergence of the meridians).

At 38 degrees North latitude:

One degree of latitude equals approximately 364,000 feet (69 miles), one minute equals 6,068 feet (1.15 miles), and one-second equals 101 feet.
One-degree of longitude equals 288,200 feet (54.6 miles), one minute equals 4,800 feet (0.91 mile), and one second equals 80 feet.

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historic topographic map of portland, or

Why don’t all USGS 7.5 minute topographic maps show the UTM grid?

For maps in the Historical Topographic Map Collection (1884-2006): Through time, policies have changed regarding whether or not a full UTM grid would appear on the 7.5-minute map series. Beginning in the mid 1950's, the grid was indicated by blue ticks around the map at 1000 meter spacing. In 1979, the ticks were replaced with a full-line black...

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...

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,...

How are different map projections used?

The method used to portray a part of the spherical Earth on a flat surface, whether a paper map or a computer screen, is called a map projection. No flat map can rival a globe in truly representing the surface of the entire Earth, so every flat map misrepresents the surface of the Earth in some way. A flat map can show one or more--but never all--...

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Bryce Canyon National Park - one of 200,000 units in PAD-US.

Date published: July 31, 2017

Mapping Public Lands in the United States

The Protected Areas Database of the United States (PAD-US) is the official inventory of public parks and other protected areas in all U.S. states and territories.

Attribution: Core Science Systems, Science Analytics and Synthesis (SAS), Environments Program, National Geospatial Program, Wildlife Program

Screen shot of topoView featuring Philadelphia 1888

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.

Attribution: Core Science Systems, National Cooperative Geologic Mapping Program, National Geospatial Program

US map of added trails and recreational points of interest

Date published: July 5, 2017

Finding Yourself Outdoors

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

Attribution: Core Science Systems, National Geospatial Program

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June 1, 2017

TopoView - A look at version 2.1

A tutorial by USGS scientist and topoView developer Chris Garrity demonstrating how to use topoView version 2.1. TopoView let's you access and download maps free of charge from the USGS's Historical Topographic Map Collection, published between 1884 and 2006.

Resources:
An Introduction to TopoView (version 1.0)

Attribution: Core Science Systems, National Cooperative Geologic Mapping Program

November 18, 2010

PubTalk 11/2010 — Silicon, Software, and Science

Monitoring the Earth's Landscape with Low-Cost High-Tech

by Rian Bogle, Remote Sensing Specialist

The USGS is one of the world's largest providers of remote sensing data, employing the best tools and techniques to expand our knowledge of the Earth.
Working with low-cost field and aerial imaging technologies,

Attribution: Western Geographic Science Center

November 18, 2004

PubTalk 11/2004 — From Plane Tables to Pixels

The Revolution in Mapping at the U.S. Geological Survey

by Susan P. Benjamin, Research Geographer

Mapping the United States in the 19th century was arduous, dangerous work; flash floods, bears, and bandits were just a few hazards
By the mid-20th century, aerial photography, photogrammetry, and stereophoto pairs, allowed

April 1, 1932

USGS Topographer at Work

Topographer George Stanley Druhot with a plane table and alidade. Recorder R.H. Moore is sitting against the Pierce Arrow in the background. A stadia rod is visible on the second car.