Projections

Geographic (Lat/Lon)

Not a true projection. Treats latitude and longitude as a square grid.

Universal Transverse Mercator (UTM)

A mapping system commonly used by the USGS for quadrangle maps. All data used in a single map must be in the same UTM zone.  The UTM coordinate system is used for the Texas Reference Frame.

UTM zones in Texas

Texas Centric Mapping System/Lambert Conformal (TCMS/LC)

A mapping system that is optimized for mapping the entire state of Texas within a single dataset.  Conformal projections are true to shape but are not necessarily appropriate for measuring area and distance.

Projection	Lambert Conformal Conic
Spheroid	GRS 80
Datum	North American Datum of 1983 (NAD83)
Longitude of Origin	100 degrees West (-100)
Latitude of Origin	18 degrees North (18)
Standard Parallel #1	27 degrees 30 minutes (27.5)
Standard Parallel #2	35 degrees (35)
False Easting	1,500,000 meters
False Northing	5,000,000 meters
Units of Measure	meters

Texas Centric Mapping System/Albers Equal Area (TCMS/AEA)

A mapping system that is optimized for mapping the entire state of Texas within a single dataset.  Equal area projections allow areal measurements and are commonly used for thematic maps.

Projection	Albers Equal Area Conic
Spheroid
Datum	North American Datum of 1983 (NAD83)
Longitude of Origin	100 degrees West (-100)
Latitude of Origin	18 degrees North (18)
Standard Parallel #1	27 degrees 30 minutes (27.5)
Standard Parallel #2	35 degrees (35)
False Easting	1,500,000 meters
False Northing	6,000,000 meters
Units of Measure	meters

For more information on map projections, please see the USGS Map Projections Poster.