This paper is an attempt to examine how aridity，an expression of water deficiency，affects metropolitan development in Texas in terms· of an ecological triangle: 1)people; 2)activity and 3)space. For the purpose of comparison， 40 cities in Texas with a population in excess of 25，000 in 1960 are selected and divided into three reference groups by precipitation. They are: Arid and Semi-arid Zone (less .than 22 inches)， Transitional Zone (between 22 and 32 inches)，and Humid Zone(more than 32 inches)
Following a brief discussion on aridity and water supply in Texas， impacts on people of the three zones are justified by population growth rates， population mobility， the elderly migration and per capita water consumption. Then， impacts on activity are examined by distribution of industry using SIC (Standard Industry Classification)， industrial water use and high-tech industries. Finally， impacts on space are addressed by urban expansion over time. Through this comprehensive analysis， it Is clear that water alone is not now viewed as the ultimate limitation to more widespread urbanization in the arid zone. However， due to blind transfer from East humid custom， one has brought with him his practices， ideas， economy from his former humid or subhumid environments. Thus， this study confirms that point and concludes that aridity had a moderate impact on metropolitan development in the arid zone and is expected to have a significant impact in the long run.