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USGS Topographical Maps


1:100 000 Scale USGS TOPO MAP Above - Image Produced By Casanova's Computer Lab Using 'ALL TOPO MAPS' Software

Map-Related Questions Are A Routine Occurrence For Us At Casanova's.  Some people are curious about various map symbols, map types, tools, while others need help with map orientation.  Many of the questions we receive regarding topographic maps are about the difference in map scales.

A Common question for US based customers, they ask; what are “township, range, and section”; technically referred to as the "Genera" Land Office Grid System.

Below We Offer Official USGS And Various U.S. Land Offices' Topo Map Facts, In a User Friendly Way; Helping To Support Our Customers And Future Casanova Outfitted Customers.  Enjoy.

USGS

The USGS took over responsibility for mapping the United States Of America In 1879; And Has Been The Primary Civilian Mapping Agency Of The United States Since.   The Best Known USGS Maps Are The 1:24,000-Scale Topographic Maps, Also Known As 7.5-Minute Quadrangles (Also Quad).   More Than 55,000 7.5-Minute Maps Were Made To Cover The 48 Conterminous States.  This Is The Only Uniform Map Series That Covers The Entire Area Of The United States In Considerable Detail.

This Entire Collection Is Made Available With Royalty Free Use In Our ALL TOPO MAPS: Series, And On A Special Central Hard Drive USGS Map Server > The ALL TOPO MAPS: V7 MAPBOX

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Official United States Government Topographic Maps

USGS Topographical Maps Available And Their Brief Description

USGS Map Series Map Scale 1 inch represents 1 centimeter represents Size
Latitude x Longitude
Minimum area** covered
7.5 minute* 1:24,000 2,000 feet 240 meters approx. 7.5 x 7.5 minutes 49sq miles
15 minute 1:62,500 1 mile approx. 625 meters approx. 15 x 15 minutes 197sq miles
30 x 60 minute 1:100,000 1.6 miles approx. 1 kilometer approx. 30 x 60 minutes 1,568sq miles
U.S. 1:250,000 1:250,000 4 miles approx. 2.5 kilometers approx. 1 x 2 degrees 4,580sq miles
* Minute refers to one minute of latitude and longitude.  A 7.5-minute map covers 7.5 minutes of latitude and 7.5 minutes of longitude.
** The minimum areas are smaller for Washington.

Referring To Large Scale And Small Scale Maps

A Brief Word About Referring To Map Scales As Large and Small.

Maps which have a scale that covers less distance, is often called a large-scale map.  And Maps With A Scale That Covers More Distance Is Called A Small Scale Map.   A Large Scale Map Displays A Larger Amount Of Subject Detail Than a Small Scale Map.   A Map Scale Of 1:24,000 (1/24,000) Would Be Called a Large Scale Map, And A Map Scale Of 1:100,000 (1/100,000) Would Be Called A Small Scale Map.

 

USGS 7.5 Minute Topographical Map Series (USGS Topo Map) (USGS Quad)

The USGS 7.5-Minute Map Series, Also Called A "USGS Quad" Map, Is The Most Detailed Available From The USGS.   The Topo Map Series Is Useful Because Topographic Features Are Easy To Identify, Which Allows For Accurately Determining Location Coordinates More Accurately.  In Addition, The Clarity Of The Topographic Features Makes Route-Finding Easier.

USGS 7.5-Minute Topo Maps Are Very Popular And Are Typically Used For Trail Exploring, Hiking, Hunting, Geologic Prospecting, Locating Real Estate, Map Making, etc.

 

30 x 60 Minute Topographical Map Series

The USGS 30 x 60-Minute Map Covers The Area Of 32 7.5-Minute Maps.   These Maps Are Useful For Four-Wheeling, Hunting And Other Activities Where Large Coverage Is More Need Than Area Detail.  This Is A Multipurpose Map Series Which Includes Most Of The Same Features On Larger Scale Maps, But With Less Detail.

 

U.S. 1:250,000 Map Series

The 1:250,000 Map Series Is The Smallest Scale.  These Maps Represent Large Areas With Less Detail.  This Map Series Is Useful For Viewing The Overall View Of An Area, But Not Good For Applications Where Detail Is Needed Or Required; Such As Navigating Over The Surface Of Land, Navigating Trails And Roads, Prospecting, etc..

 

Township, Range & Section

In 1812, the U.S. Government formed the General Land Office (renamed the Bureau of Land Management in 1946) to create a standardized system to more accurately define a given U.S. location.   This system was initiated in response to the acquisition of large tracts of land, like the Louisiana Purchase, during the 1800s.   The system developed by the Government Land Office is called the 'General Land Office Grid System' and is used in states west of Ohio, as well as part of Ohio.  The system divides land into 36-square-mile units called 'townships'.   Each township has a township and range designation shown in red print as to define its 36-square-mile area.  A township is numbered north and south from a selected parallel of latitude called a 'base line', and range is numbered west or east of a selected meridian of longitude called a 'principal meridian'.

Townships are sub-divided into 36 1-by-1-mile parcels called sections. Sections are numbered from 1 to 36 for identification.   Sections are broken into quarters, which are further quartered to describe a property location.

The Land Office Grid system is used for legal land descriptions.

A Great Township, Range And Section Tool Can Be Had With Using ALL TOPO MAPS.  Enjoy Working With A Automatic Public Land Survey Coordinate Plotting And Use Feature With ALL TOPO MAPS PLS

 

Public Land Survey System

In 1796 the United States Congress enacted a method of dividing public domain lands into theoretical six mile square units known as ‘Congressional Townships’.  Townships are based from a central set of orthogonal axis, the North-South axis is called the ‘Principal Meridian’, the East-West axis is called the ‘Base Line’.  Townships are consecutively numbered to the North and South and Ranges are numbered from East to West.

Each Township is divided into a six by six grid of 1 mile squares called sections. Sections are numbered in a serpentine fashion from the North East corner of the township. If perfect, each section would encompass 640 acres. Sections are additionally divided in to 160 acre quarters, and then into 40 acre quarter quarters.

Since the meridians and base lines are not truly parallel, no townships are perfectly square. Where different axis meet there are very significant errors. Early surveying errors added additional imperfections.

In spite of all the errors, the Public Land Survey system still accurately defines a point-on-the-ground or parcel by Principal Meridian, Township, Range, Section and offset.

The various scales of topographic maps have traditionally shown sections and townships. On a released 7½ minute quadrangle, township and range are identified in the map collars.

When using digital map products, it is difficult to pan to the edge of a map and find the Township and Range for a given section.   Many digital products de-collar the maps (these are called "seamless maps"), which makes determination of Township and Range impossible.  The Solution, ALL TOP MAPS: V6 & V7 With PLS Tool

 

National Forest Topo Maps

USGS-USDA Forest Service Single-Edition Quadrangle Maps

In August 1993, the U.S. Geological Survey and the U.S. Department of Agriculture’s Forest Service signed an Interagency Agreement to begin a single-edition joint mapping program.  This agreement established the coordination for producing and maintaining single-edition primary series topographic maps for quadrangles containing National Forest System lands.   The joint mapping program eliminates duplication of effort by the agencies and results in a more frequent revision cycle for quadrangles containing National Forests.   Maps are revised on the basis of jointly developed standards and contain normal features mapped by the USGS, as well as additional features required for efficient management of National Forest System lands.  Single edition maps look slightly different but meet the content, accuracy, and quality criteria of other USGS products.

 

USGS Topo Mapping Software CasanovasAdventures.com

Official USGS Maps In Digital Software Format

The USGS Has Scanned Their Entire Collection Of Topo Maps Into Digital Images.  The Scanned Paper Maps Are Saved As Digital Image Files For Use By Computer Programs.   The USGS Has Identified These Digital Map Image Files As 'Digital Raster Graphics' or DRG for short.

Casanova's Has Made Obtaining And Working With DRG Maps Easy And Cost Effective, For Commercial And Private Applications.  When First Defined And Produced As The New USGS Digital Map Standard, The USGS Provided These Large Digital Image Files Online At No Cost.  Since Then Things Have Changed.  Some Web Sites Are Now Charging For The Files Under Different Schemes Like "CD WRITE FEE"!    The Files Are Huge And Require Longer Downloading Times, And Specially Written Software To Actually Put Them To Any Type Of Practical Mapping Use.  Since Their First Release, Our Map Expert Has Been Researching and Monitoring The Mapping Community (Industry) For Practical And Quality Applications And Software For The New Technology.   Today Casanova's Offers Several Unique USGS Mapping And Navigation Applications Plus The Entire USGS DRG Collection, With Older Out Of Print Maps At Extremely Cost Effective Levels For Both The Private And Commercial Users.

 

by Gene Casanova

CasanovasAdventures.com

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