Sources: GM to shut many US plants up to 9 weeks - Yahoo! Finance DETROIT (AP) -- Two people briefed on the plan say General Motors Corp. will close most of its U.S. factories for up to nine weeks this summer because of slumping sales and growing inventories of unsold vehicles. The people did not know exactly when the shutdowns would occur, but both say they will include the normal two-week closure in July to change from one model year to the next. Neither person wanted to be identified because workers have not been told of the shutdowns. GM spokesman Chris Lee would not comment other than to say the company notifies employees before making any production cuts public. GM is living on $13.4 billion in government loans and faces a June 1 deadline to restructure or seek bankruptcy protection.