Borders are perhaps the biggest and most contentious issue when it comes to trade, immigration, diplomacy, and innovation. Twenty years after NAFTA and with the Trans-Pacific Partnership on the horizon, it's time to update the United States' border-sharing relationships with its neighbors. One provocative way to start the conversation: Let's create a North American passport, say Andres Martinez and Daniel Kurtz-Phelan in this conversation with Anne-Marie Slaughter (and in New America's Big Ideas series on CNN). Martinez and Kurtz-Phelan point out that the privileges of movement and access shared among the United States, Canada, and Mexico should reflect just how interwoven our respective economies--including education, manufacturing, and research, in addition to trade itself--have become.