Can you see that herd of elk up ahead in Yellowstone National Park? Or is it obscured by the dozens of cars stacked up in traffic? When Yellowstone's Grand Loop Road was built on top of wagon tracks after the turn of the century, engineers never imagined how popular the world's first national park would become. Replacement of the Grand Loop, which began in 1987, will end up costing more than $1 billion, according to parks advocates. That money won't come out of NPS's appropriated budget, which only covers minor maintenance like snowplowing, patching and restriping. It will come out of the federal highway bill, whose allocation for the Park Service has been flat at $240 million since 2009 and been stretched for the past two years to cover that agency's transit projects, too.