That's not technically within the borders of Great Smoky Mountain National Park, but rather on the Blue Ridge Parkway. A Depression era public works project that runs along the ridgeline of a mountain range, and connects Smoky Mountain with Shenandoah National Park.
This was plus or minus October 10th or so, when the foliage is at its peak. I live in New England (the most northeastern region of the US, including Boston) and we've pretty much got the market cornered on fall foliage. We must have been the only people last year to get out of New England to see the colors.
The National Parks are a passion of my wife and me. Been to 23, got 35 to go. I've got more pictures like that than I can shake a stick at.