I measured the ups of the AT Centerline on Google Earth.
Registered the elevation at every 1/8 mile and compared the elevation gain.
Here my results for the steepest quarter miles between Springer and Damascus:
Day State between and gain (in feet) % 9 NC Mooney Gap Albert Mtn Firetower 394 30,0 31 TN/NC Laurel Fork Sh Pond Flats 338 25,8 13 NC Sweetwater Gap Brown Fork Gap Sh 325 24,8 32 TN/NC Watauga Dam Rd Vandeventer Sh 325 24,8 31 TN/NC Laurel Fork Sh Pond Flats 322 24,5 12 NC Grassy Gap Swim Bald 315 24,0 13 NC Brown Fork Gap Sh Brown Fork Gap 213 23,8 27 TN/NC Nolichucky River Curley Maple Gap Sh 308 23,5 4 GA Tesnatee Gap Wildcat Mtn 305 23,3 28 TN/NC Hughes Gap Ash Gap 305 23,3 23 TN/NC Little Laurel Sh Camp Creek Bald 302 23,0 16 TN/NC Spencer Field Sh Rocky Top 292 22,3 28 TN/NC Cherry Gap Sh Iron Mtn Gap 292 22,3 28 TN/NC Hughes Gap Ash Gap 292 22,3 22 TN/NC Hot Springs Lovers Leap Rock 289 22,0 25 TN/NC Low Gap Big Bald 282 21,5 5 GA Unicoi Gap Rocky Mtn 279 21,3 7 NC Bly Gap Sassafras Gap 279 21,3 32 TN/NC Watauga Dam Rd Vandeventer Sh 279 21,3 3 GA Woody Gap Big Cedar Mtn 276 21,0 24 TN/NC Rector Laurel Rd Frozen Knob 276 21,0 28 TN/NC Ash Gap Roan High Knob Sh 276 21,0 2 GA Horse Gap Sassafras Mtn 272 20,8 28 TN/NC Ash Gap Roan High Knob Sh 272 20,8 30 TN/NC Mt Harbor Hostel Buck Mtn Rd 272 20,8