The major physiographic provinces of the 48 conterminous United States.
This map is based on public domain data from the USGS[1]

Originator: Fenneman, N.M., and Johnson, D.W.
Publication_Date: 1946
Title: Physiographic divisions of the conterminous U. S.
Geospatial_Data_Presentation_Form: map
Publication_Place: Washington, DC
Publisher: USGS
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"
Own work
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