Immigration and trade across the border of the United States with Mexico is perhaps the most heated point of division in politics today. But for most of its length, the border is a line drawn on the map with little consideration of the environmental, economic or social realities of the communities and ecosystems it passes through. Each of the four border states will be discussed to correlate how the environment has shaped the human population and how humans in turn have reshaped the border environment. Each session will briefly review the geography and history of one area, followed by discussion of the specific impacts caused by the construction, continuing operations and maintenance of border security infrastructure.