The 1983 La Paz Agreement between the United States and Mexico is a pact to protect, conserve, and improve the environment of the border region of both countries. The agreement defined the region as the 62 mi (100 km) to the north and south of the international border. This area includes maritime (sea) boundaries and land in four American states and six Mexican border states.

Representatives from the two countries signed the agreement on Aug. 14, 1983, in La Paz, Mexico. The agreement took effect on Feb. 16, 1984. It established six workgroups, with each group concentrating on an environmental concern. Representatives from both countries serve on the workgroups that focus on water, air, hazardous and solid waste, pollution prevention, contingency planning and emergency response, and cooperative enforcement and compliance.

In February of 1992, environmental officials from the two countries released the Integrated Environmental Plan for the Mexican-U.S. Border Area. The Border XXI Program created nine additional workgroups. These groups focus on environmental information resources, natural resources, and environmental health.

Border XXI involves federal, state, and local governments on both sides of the border. Residents also participate through activities such as public hearings.