Significant declines in acid deposition has been reported in the eastern United States, particularly sulfate since the mid-2000s.  Annual declines in acid deposition have also been observed in Great Smoky Mountains National Park (GRSM) at the Noland Divide high-elevation monitoring station.  Since 1991, this monitoring station continues to collect wet deposition, throughfall, and soil and stream chemistry.  After 2008 significant declines in annual loadings and average concentrations were recorded.  Annual sulfate loadings prior to 2003 were generally above 100 kg/ha, and prior to 2008 were above 60 kg/ha.  After 2008, annual sulfate loadings have been consistently below 15 kg/ha and coincides with the installation and operation of air pollution controls at two Tennessee Valley Authority coal fired power plants in East Tennessee.  Stream sulfate in the Noland Divide watershed has shifted from mass retention as reported for years prior to 2003 to now mass export.  However, stream sulfate concentrations have not statistically changed around 40 µeq/L, but may have declined slightly though continued long-term monitoring is needed to detect a trend due to annual variability.  Stream pH at the Noland Divide site has increased slightly from about 5.6 in 2006 to 5.8 in 2019.  Because of the major decline in annual sulfate and nitrate deposition at Noland Divide, it assumed the same would be observed throughout the GRSM.  The last park-wide mapping of acid deposition was conducted by Weathers and others in 2000.  In the Weather’s study, elevation was a dominant factor to annual deposition loadings, where below 1000 m sulfur was about 5 kg/ha and above 3000 m it was about 45 kg/ha.  Similar annual loading trends were observed for inorganic nitrogen.  In 2016 a park-wide survey of throughfall deposition was conducted to update our understanding of changes that has occurred.  A total of 22 sites among seven watersheds were selected along an elevation gradient in which annual sulfur loadings ranged from 1.47 kg/ha to 7.17 kg/ha, and inorganic nitrogen ranged rom 1.84 kg/h to 9.05 kg/ha.  As would be expected, the annual loadings for sulfur and inorganic nitrogen had significantly declined.  However, an elevation gradient of annual loading was not significant.  In contrast, there was a significant elevation gradient for pH and acid neutralizing capacity (ANC) from means of about 6.0 and 90 µeq/L at 1000 m to 5.6 and 15 µeq/L at 2000 m, respectively.  Research related to the base cations in throughfall deposition is on-going.