The major physiographic provinces of the 48 <a href="https://en.wikipedia.org/wiki/Contiguous_United_States" class="extiw" title="en:Contiguous United States">conterminous United States</a>.
<p>This map is based on public domain data from the <a href="https://en.wikipedia.org/wiki/United_States_Geologic_Survey" class="extiw" title="en:United States Geologic Survey">USGS</a><a rel="nofollow" class="external autonumber" href="https://water.usgs.gov/GIS/metadata/usgswrd/XML/physio.xml">[1]</a>
</p>
<dl><dd>Originator: Fenneman, N.M., and Johnson, D.W.</dd>
<dd>Publication_Date: 1946</dd>
<dd>Title: Physiographic divisions of the conterminous U. S.</dd>
<dd>Geospatial_Data_Presentation_Form: map</dd>
<dd>Publication_Place: Washington, DC</dd>
<dd>Publisher: USGS</dd></dl>
The data is presented in an Lambert equal area projection described in "proj" format as: "+proj=leac +lat_1=29.5 +lat_2=45.5 +lat_0=23 +lon_0=-100 +x_0=0 +y_0=0 +ellps=clrk66 +datum=NAD83 +units=m +no_defs"
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