Mexico is already the world's single largest buyer of U.S. natural gas. But it's building infrastructure that will bring in even more. And that strategy is attracting growing resistance from communities who worry about projects in their backyards and environmentalists who say they will increase pollution and deepen energy dependence on the U.S. One example is the Southeast Gateway Project, which added 435 miles to a pipeline running all the way from southern Texas to the doorstep of the Yucatan Peninsula. Mauricio Contreras, who has fished in the Gulf of Mexico for more than 40 years, worries that leaks from the pipeline could devastate his way of life. The government and Canadian company TC Energy argue the pipeline is necessary and safe.