Summer traffic in Los Angeles. Summer’s ending on a sweet note for U.S. drivers. At an average of $2.44 a gallon, nationally, Americans are paying the cheapest price for gasoline over a Labor Day holiday weekend since 2004, according to separate forecasts from the U.S. Energy Information Administration and AAA. Thank crude oil’s 13 percent plunge this year to $46.17 a barrel as of Friday on the New York Mercantile Exchange for relief at filling stations. That’s the lowest, seasonally, in at least a decade. None of it would be possible without the oil wells in shale drilling deposits gushing near the highest level in 40 years, leaving refineries awash in petroleum. Speculation that Iran’s exports will exacerbate a global glut have also helped keep oil in check. This weekend’s Labor Day holiday in the U.S. marks the unofficial end of summer driving season as teenagers return to school […]