I think we’re ready for the next level in ecoregions. In this case, it’s level II.
Here is a link to the PDF map. It’s still a little hard to read online, but we’ve clearly left the elementary version of ecoregions and are starting to get into a little more detail.
ftp://newftp.epa.gov/EPADataCommons/ORD/Ecoregions/cec_na/NA_LEVEL_II.pdf
The GPT passes through at least five ecoregions at this level including, from south to north) Upper Gila Mountains, Warm Deserts, South-Central Semi Arid Prairies, West-Central Semi Arid Prairies, Western Cordillera, and if it ends in North Dakota, it would pass through the Temperate Prairies as well.
