On January 25, 2017, during his first week in office, President Donald Trump signed an Executive Order calling for the “immediate construction of a physical wall on the southern border” of the United States. Such a wall would span more than one thousand miles, across many different habitats and many different communities. Before a wall can be built, numerous questions must be answered: Which environmental laws apply? How might all this work? On February 16, ELI convened experts to discuss how environmental law and policy may interact with the Executive Order and to spark discussion about important environmental resources and communities along the border. Below, we present a transcript of the event, which has been edited for style, clarity, and space considerations.