Texas County Map Parameter Reference
This page explains the technical details behind MidTex Texas County Maps—source dates,
datums (NAD27 vs NAD83), projections, file formats, and the layers included in each product.
For a general overview of the maps themselves, pricing, and ordering, please visit the
Texas County Oil & Gas Maps page.
Source Date
Source Date is an indication of when the information was last updated. Some entries
will include a date in the past, like 2026-01-31 (Jan 31, 2026), while others will
indicate "UPDATED UPON ORDER". Files with a date in the past let you know that some
formats will be available for immediate download upon successfully ordering the map,
while all requests that indicate a Source Date of "UPDATED UPON ORDER" will require
processing time (usually 1 business day, occasionally 2) before the files are uploaded
and ready to download from your account. In the case of processing time, you will be
notified when the file(s) are ready for download.
Datum
Datum types that are supported by our system are NAD27 and NAD83. NAD stands for
"North American Datum". 27 and 83 refers to the years 1927 and 1983, respectively.
Simply put, the datum ultimately refers to the parameters used to approximate the shape of the
earth. With the advent of the GPS satellite constellation, it has been possible for us to get
closer and closer approximations of the spheroid of the earth (as the earth is not
a sphere, but a spheroid, which means that it is slightly oval). While a number of
approximations have been used throughout the years, the two utilized by NAD27 and NAD83
are the most popular for mapping in the United States.
Which one should I use?
It depends upon your circumstances. Below are some factors that may play into your
decision, if you are not sure.
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NAD27
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- NAD27 is an older datum. (In truth, the spheroid parameters utilized by NAD27 is
the CLARKE 1866 spheroid. With the GPS constellation, we have been able to get
much closer to the approximation of the earth. That being said, it is quite amazing
that Mr. Clarke got as close as he did, using the equipment of his day.)
- NAD27 is still the most popular datum downloaded from our system, even though it
is not the more accurate datum, due to the fact that many systems in place continue
to use NAD27 extensively.
- If you are confused, and don't know what to choose, NAD27 is a good default choice.
- Conversions between NAD27 and NAD83 always introduce additional error, depending
upon the method utilized. Some approaches are more accurate than others, but in
the end, they all add additional error. It is best to choose the
one that you predominatly work in the most to mitigate this issue.
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NAD83
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- NAD83 is the way of things currently.
- GPS uses GRS80, which is the ellipsoid utilized by NAD83 as well
- Plotting GPS information may in some cases be easier and more direct with maps
already in NAD83. (Many systems will make this seamless, however)
- Wellspots (if included in the product you purchase) will be in the
datum of the map. Many like to upload these locations into their GPS
handhelds when doing recon work to locate wells. NAD83 may make this process
less error prone.
- Conversions between NAD27 and NAD83 always introduce additional error, depending
upon the method utilized. Some approaches are more accurate than others, but in
the end, they all add additional error. It is best to choose the
one that you predominatly work in the most to mitigate this issue.
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Projection
Due to the fact that the earth is not an actual sphere, (as well as the fact that the landscape
is not uniform), it is absolutely impossible to determine a system that would give 100% precision
when determining location, be it with Latitude and Longitude or any XY type of system. Therefore,
any location is always based on projection of some kind.
Projections supported by our system are: Lat-Long, SPCS (State Plane Coordinate System), and UTM
(Universal Transverse Mercator).
Zone
Zone is necessary when using a "flat-grid" projection system, like SPCS or UTM. (Zone has no
meaning when using Lat/Long projection). Since flat-grid systems work in a localized area only,
it is necessary to further determine which area that you are working in. For example, The Texas
SPCS is divided into 5 zones, numbered from 4201 through 4205. The zones are oriented in wide bands
from west to east. The UTM system, however, is oriented in north/south bands that go from the South Pole all the
way to the north pole.
Units
The units that our system uses are: Decimal Degrees (used exclusively with Lat/Long projection),
US Feet, and Meters. US Feet and Meters may be specified with any flat-grid projection (SPCS or UTM).
File Format
Our system supports the following file formats: DWG (AutoCAD Drawing), DXF (AutoCAD Drawing
Exchange Format), DWF (AutoCAD Drawing for the Web Format), PDF (Adobe Portable Document Format),
SHP (ArcInfo GIS Shape File), and E00 (ArcInfo Exchange Format).
For more specific information on what these file formats are, and what their optimal usage is,
please visit the Texas County Map Requirements page.
Layers Included
Map files have multiple layers that may be included in the download. Currently, the Texas
County Maps include these layers:
| Texas County Map: Available Layers |
| BASE |
The base layer includes airports, cemeteries, roads, rivers and water features,
shorelines, railroads, and boundaries (city, county, state, and government lands) |
| TEXAS LAND GRID |
The Texas Land Grid layer includes blocks, sections, surveys, abstracts,
and subdivision information. |
| PIPELINES |
The Pipelines layer includes pipelines, as well as embedded pipeline attribute
information (only in selected file formats). |
| WELLSPOTS |
The wells layer includes the well symbols and API number (where available). |
Pipeline Attributes
Indicates whether or not the map that you are interested in includes the pipeline attributes.
Some formats do not allow embedded attribute information, or will not allow it to be utilized by
the target application, while others will. Notably, DWG, DWF, SHP, and E00 formats work well with
attribuate, while DXF and PDF do not.
For more information on pipeline attributes that may be included with the map, please see the
Pipeline Attributes section of
our site.
Well Information
Currenly, our system supports two levels of well information: Basic and Extended. Below is a
description of what is included in each level:
| Texas County Map: Available Layers |
| Basic |
Basic well information includes well location (X,Y, or Lat/Long, depending on
the product that you purchase), API # (where available), and symbol type (oil, gas, dry, etc). |
| Extended |
Extended well information includes well location(X,Y, or Lat/Long, depending on
the product that you purchase), API # (where available), symbol type (oil, gas, dry, etc.),
Quad Number, Survey, Block, Section, Abstract, Total Depth, Permit Number, Lease Name,
Lease Number, Well Number, Field Name, Completion Date, Plug Date, Reference API,
On/Off Schedule, Operator, and Oil Gas Code. For more information on this product, please
see the Texas Well Data section of our site. |
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