Every 12 years, the U.S. and Mexican political calendars sync up and both countries hold their presidential elections. The last time this happened, in 2000, Mexicans voted in Vicente Fox, ushering out of power the Institutional Revolutionary Party (PRI), which until then had been one of the longest-ruling political parties in the world. Meanwhile, the United States said good-bye to President Bill Clinton and hello to the George W. Bush administration. Twelve years later, power in Mexico has once again changed hands with the presidential victory of Enrique Peña Nieto, who is head of the rebuilt PRI. And this week, the United States has a choice between granting Barack Obama another four years in the White House and pushing him out in favor of the Republican nominee, Mitt Romney. When the electoral scuffles are over, Mexico and the United States will have an opportunity to reboot their bilateral agendas and improve relations as they work on perennial challenges such as migration and drug trafficking.