In 1983, the US and Mexico signed the "La Paz Agreement" which defined the border zone as the region situated 60 miles (100 kilometers) on either side of the 2,000-mile international boundary between the US and Mexico. The BRITE also uses this definition. This region encompasses approximately 240,000 square miles of diverse ecological territory that include wetlands, semi-arid, desert, and coastal regions.

The various environment issues of the US–Mexico border region are being examined in different segments. Currently, the ATR Institute (ATRI) has gathered information on Air Quality, Water Quality, Habitat, and Land Use. Articles on these topics relevant to policy development and to additional research are among the documents selected for the bibliography. Future plans include adding topics, such as Hazardous Waste Transportation, Noise Pollution, and Regulations concerning transportation and the environment. .

1. Information that covers a more general area but is applicable to the border region.
2. Information using GIS. Researchers see the value of using GIS in transportation/environment research; GIS is an effective tool for mapping environmental impacts.
3. Models that were created in another region that could be transferred to border region
4. Habitat behavior models. It is hoped that models of animal behavior outside of the border region can be used to gain insight on animal behavior within the border region.

Transportation includes passenger and commercial vehicles, railroads, airplanes, and ships. Off-road vehicles are not included in this study because data for their use was not available.

The "La Paz Agreement" focused on promoting cooperative efforts to address environmental issues along the defined US – Mexico border area. This agreement also establishes that the two countries will "cooperate in the field of environmental protection in the border area on the basis of equality, reciprocity, and mutual benefit."