In March 2020, at the start of the pandemic, the U.S. sealed its border with Mexico. The purpose, U.S. officials said, was to protect Americans from the spread of Covid-19. But in the neighboring cities of Nogales, Arizona and Nogales, Sonora, Mexico, the unintended consequences of the border closure have come into sharp focus. In addition to Covid-related deaths, the economy on the U.S. side has been devastated. Meanwhile, business on the Mexican side is booming. What does this shift in the economic center of gravity mean for a region where travel and migration across the border has been a part of life for generations? Producers Maritza Felix and Julio Cisneros visit both cities to learn.