The National Park Service would be forced to delay the opening of roads into iconic national parks including Yellowstone, Grand Canyon and Yosemite by as much as a month if Congress fails to avert $85 billion in across-the-board spending cuts, according to new information obtained by a Park Service retirees group. In addition, nationwide reductions in staff, maintenance crews and operating hours would affect hundreds of millions of visitors, according to the Coalition of National Park Service Retirees.