Borders create separations but they are also meeting points, as well as frontiers where new experiments in bilateral cooperation are tested. This talk will use the US--Mexico border to explore the overlaps between migration and environmental issues. As it slices between nations, a border wall would block animal migration corridors in one of North America’s most biodiverse regions. Environmental factors such as drought and climate change will continue to affect human migration patterns in the future, and they will make undocumented border crossing more dangerous, contributing to the hundreds of environmentally-caused deaths that occur each year in America’s southern deserts and rivers. Yet along the border, there are also international collaborations between scientists, bureaucrats, and conservationists, such as transboundary protected parks and water-sharing agreements over the Rio Grande. This talk is intended to provoke discussion and will feature more questions than answers.