·  This is a Mercator projection of my hometown, Elizabethtown, PA.

·  The coordinates of my hometown (in decimals) are 40.155331 N and 76.602545 W. This map is bounded between 35°N and 45°N, and 81°W and 69°W.

·  The Mercator projection is a conformal projection, in that the angles between points are preserved.  There isn't any distortion at the equator, but since my hometown is nowhere near the equator, there is increasing size distortion as the map moves northward.

·  I used Online Map Creation to customize and create this map.

·  I learned that, even on a smaller scale, the distortion in area size on a Mercator projection is still very noticeable. Vermont and New Hampshire look huge compared to states such as Virginia that are closer to the equator.

Geographic Coordinates
The place name shown on the map above represents the location of my home town. The geographic coordinates of my home town are:

Latitude: 40° 09' 19" N, Longitude: 76° 36' 09" W

·  It uses the system of longitude and latitude to locate places on a spherical earth.  The basis for latitude is the equator (0°), and the basis for longitude is the prime meridian (0°).

UTM Coordinates
The UTM coordinates (NAD83) of my home town are:

Easting: 363518.391 meters, Northing: 4446222.736 meters, Zone: 18

· The UTM coordinate system is based on a flat grid of the earth rather than a spherical one. It only has a north-south range of 164° as opposed to the spherical range of 180°.

Instead of positive and negative values that come from a -180 to +180, every value is positive starting at zero. It consists of 60 zones, each 6° wide. In order to find a location, the unique coordinate zone must first be determined before it is found.
·  NAD83 and NAD27 are two different North American Data coordinate systems used to graph the United States. NAD27 is based on a spheroid from 1866 whereas NAD83 is based on the Geodetic Reference System 1980 ellipsoid. Satellite and terrestrial data is used as opposed to NAD27 which just used land data. Because of these differences, NAD83 improved accuracy of the coordinate system and is different from NAD27 by up to 300 feet in the Western United States.

State Plane Coordinates
The State Plane coordinates (NAD83) of my home town are:

Easting: 697761.716 meters, Northing: 91899.384 meters, Zone: PA S

·  In the state plane coordinate system, the world map is divided into zones.  As of 1983, the U.S. was divided into 122 different zones.  Each zone is based on a transverse Mercator or Lambert Conic conformal projection in order to minimize scale distortion. The coordinate system is an (x,y) system.

·  The geographic coordinate system is completely global, but its disadvantages include negative numbers in calculations, and necessary arc-to-decimal conversions throughout. The UTM coordinate system is nearly global in its extent, with reasonably low error.  All of the calculations deal with positive coordinates, as does the State Plane coordinate system.  However, a disadvantage is the sheer number of UTM zones, ten across the United States, which can often make things confusing. If you plot two cities without knowing that they are in separate zones, you could end up plotting the cities in reverse. The State Plane coordinate system is more accurate than the UTM system.

Sources

Dana, Peter H. (2000) Map Projection Overview http://www.colorado.edu/geography/gcraft/notes/mapproj/mapproj.html Accessed 4 October 2004.

DiBiase, David (2002) Understanding Geographic Data. Module 1: What Are Geographic Data? ESRI Virtual Campus http://campus.esri.com Accessed 4 October 2004.

National Geodetic Survey (2002) NADCON - North American Datum Conversion Utility. http://www.ngs.noaa.gov/TOOLS/Nadcon/Nadcon.html Accessed 29 September 2004.

National Geodetic Survey (2002) SPC Utilities. http://www.ngs.noaa.gov/TOOLS/spc.html Accessed 29 September 2004.

National Geodetic Survey (2002) UTM Utilities. http://www.ngs.noaa.gov/TOOLS/utm.html Accessed 29 September 2004.

United States Geological Survey (2000) Map Projections. http://mac.usgs.gov/mac/isb/pubs/MapProjections/projections.html Accessed 29 September 2004.

Weinelt, Martin (2002) Online Map Creation. http://www.aquarius.geomar.de/omc/ Accessed 29 September 2004.