With the growing prominence of global city regions as drivers of today’s economy, there is a need to reposition large urban areas to be competitive in this context. The success of the European trans-national urban model has raised considerable interest in the United States to delineate a similar network of multi-city mega regional systems. It has been predicted that most of the growth in this country in the next 50 years will be concentrated in about 10 such emerging mega-regions. The Texas Triangle is one such mega-region. As much as 70% of the state’s population in 2050 is expected to be concentrated within this triangular mega region, defined by the MSAs of Dallas-Fortworth, Austin-San Marcos, San Antonio and Houston. This study attempts to identify the exact spatial extent of this region based on several parameters, but primarily focusing on a network of natural environmental systems within the proposed Triangle region. / text