The world is watching for the impact of history's first downgrading of the credit rating of the United States. How important is it? How worried should Americans be? The Dow Jones Industrial Average closed down 634 points today, a loss of 5.55 percent. The NASDAQ dropped 175 points, losing 6.9 percent. John Blank, Deputy Chief Economist for the Los Angeles County Economic Development Corporation, considers the impact in Southern California.