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Tamaulipas-Texas Semiarid Plain

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NameColor on MapCEC Code*
Southern Texas Plains9.6.1

* This code refers to the CEC's Level 3 ecoregion codes for North America, see here.

About the Tamaulipas-Texas Semiarid Plain

The Tamaulipas-Texas Semiarid Plain is a level 2 ecoregion representing the southernmost portion of the Great Plains, excluding the coastal plain. It stretches from South Texas into the Mexican states of Tamaulipas, Coahuila, and Nuevo León. In Texas this region is known as "Brush Country". The Rio Grande is one of the major features in this region, and marks the border of Texas and Mexico.

The topography somewhat irregular, with plains and rolling hills. The climate is a dry subtropical steppe climate. There is some seasonality: summer brings much hotter temperatures, and spring and fall have the highest rainfall, with winters being drier than summer. Being subject to continental influences and without the moderating influence of water, large, unpredictable swings of temperature can occur, including hot, dry spells, as well as significant cold in winter. Rainfall is also unpredictable. Long spells of drought, often severe, are common, but tropical storms and other weather patterns bringing moisture off the gulf can also lead to significant rainfall.

This region was originally dominated by grassland and savannah, but the influence of humans has converted much of it into thorny brush.

An overwhelming majority of the land here is now used for grazing cattle. There is a small amount of cropland in the northernmost part of this region, as well as in the floodplain of the Rio Grande. Most of this region is sparsely populated, with only small settlements. Laredo/Nuevo Laredo is a small metro area at heart of this region, which is situated roughly halfway between San Antonio and Monterrey, two larger metro areas both just outside this region.

To the north, this region transitions gradually into the slightly cooler South Central Semi-Arid Prairies; to the east, along the coast, the wetter, milder, flatter Texas-Louisiana Coastal Plain. Directly west, inland, lie a vast expanse of Warm Deserts. To the southeast lie the Dry Gulf of Mexico Coastal Plains and Hills which are wetter overall but have a stronger seasonality of precipitation and milder winters. To the southwest is a more abrupt border with the Eastern Sierra Madre mountains.