The U.S. debt ceiling crisis had an unnecessary negative impact on the economy, President Barack Obama said on Wednesday, while a congressional impasse over aviation could cost the government $1 billion in lost revenues. Obama signed legislation into law on Tuesday that would raise the U.S. debt ceiling and cut spending, averting a default hours before a deadline. "The economy is still weakened, partly because of some things we couldn't control like the Japanese earthquake and the situation in Europe as well as the Arab Spring and its effect on oil prices," Obama told reporters at the White House at...