"Some 247,000 jobs were lost in July, a number that under ordinary circumstances would send a shudder through the country," columnist Bob Herbert wrote. "It was the smallest monthly loss of jobs since last summer. And for that reason, it was seen as a hopeful sign. The official monthly unemployment rate ticked down from 9.5 percent to 9.4 percent."But behind the official numbers is a scary story that illustrates the single biggest challenge facing the United States today. The American economy does not seem able to provide enough jobs — and nowhere near enough good jobs — to maintain the standard of living that most Americans have come to expect."The country has lost a crippling 6.7 million jobs since the Great Recession began in December 2007. No one is predicting a recovery in the foreseeable future powerful enough to replace the millions of jobs that have vanished in this historic downturn."