The
Trans-Pecos, as originally defined in 1887 by the Texas geologist
Robert T. Hill, is the portion of
Texas that lies west of the
Pecos River. The term is considered
synonymous with
"Far West Texas", a subdivision of
West Texas. The Trans-Pecos is part of the
Chihuahuan Desert, the
largest desert in North America. It is the most mountainous and arid portion of the state, and most of its area (outside the city of
El Paso) is vast and sparsely populated, comprising seven of the ten largest counties by area in Texas. The area is well known for the natural beauty of the
Big Bend, and has one of the highest proportions of publicly owned land in the continental US.