The adverse health effects of exposure to high levels of ultrafine particulate number concentration have been widely reported. New York State (NYS) borders southeastern Canada and the Great Lakes Region and is influenced by air pollutants from these upwind source regions. Through comparison of observed and simulated CN10 (condensation nuclei >10 nm) at rural and remote sites in NYS, we show that Canada anthropogenic and the Great Lakes Regions shipment SO₂ emission (CAGLESO2) significantly influenced CN10 in NYS. These emissions on average produced a 22% enhancement of CN10 in NYS in 2017, varying from 40% in Northwestern NYS to 10% in Southeastern NYS. We also found that the impact of CAGLESO2 on NYS’s CN10 in 2017 was 2.5 times higher than that in 2005 and 1.6 times higher than that in 2011, which indicated increasing influnece of CAGLESO2 on CN10 in NYS over the last decade.