The U.S. became a net oil exporter to Mexico for the first time in more than 20 years as output from shale fields pushed the world’s biggest consumer toward energy independence. Net exports — comprising only oil products since the U.S. bans most shipments of crude — totaled 48,000 barrels a day in July, the U.S. Energy Information Administration said in data released Wednesday. A decade ago, the country bought a net 1.3 million barrels of oil from its southern neighbor. The emergence of the U.S. as a net supplier to Mexico underscores how the growth of the shale industry is redrawing the global energy map. Output from shale rocks pushed U.S. oil production to a three-decade high earlier this year, driving down prices, boosting margins for refiners and fueling a debate over whether the country should lift restrictions on exports of crude. U.S. net oil imports from Mexico […]