As an organizer working for the Sierra Club along the U.S.-Mexico border, Oliver Bernstein sees firsthand the messy interplay between poverty and the environment. In Mexico, activists and residents struggling with booming industrialization are fighting for cleaner air and water, but also for a decent standard of living in their low-income communities. Meanwhile, their American neighbors seem to be focused mainly on protecting natural areas. Bernstein weighs in on the U.S. movement's oversights.