Nantucket, MA Coastal Erosion Rate
Shoreline change 3 miles southeast of Nantucket, MA
USGS's shoreline-change data puts this stretch, 3 miles southeast of Nantucket, MA, at 2.71 feet of erosion a year on average, a long-term rate for this specific ~3.5-mile section, not one storm's damage. At that rate, the shoreline has lost roughly 27.1 feet over the last decade.
What "Nantucket" means on this page
USGS surveys the coast in transects spaced a few hundred feet apart; this page groups the nearest ones into a single ~3.5-mile reading for the stretch closest to Nantucket, MA, rather than showing one arbitrary line. Segment center: 41.25, -70.05. USGS's New England / Mid-Atlantic assessment last surveyed this stretch through 2007-2009, computing the rate with its LRR method. Other US regions were surveyed in different years, sometimes decades apart, so this page states its own rather than implying one national vintage.
What 2.71 ft/yr means over time
Run 3 miles southeast of Nantucket, MA's 2.71 ft/yr rate forward 25 years and it implies about 68 feet of further retreat, assuming nothing changes, which is exactly the assumption a seawall or nourishment project exists to break.
Where this fits nationally
This reading comes from 84 individual transects averaged together, 100% of which measured erosion rather than growth. Uncertainty on this specific number: 0.4 ft/yr either side. Sorted from fastest erosion to fastest growth across all 1211 measured segments nationally, this one lands at 102. Source: USGS Open-File Report 2010-1119. Siasconset, MA sits at national rank 302 for erosion (0.48 ft/yr), one reference point among the 1211 scored segments, 5 miles from here. 2.6 miles up the coast, Nantucket, MA shows 0.8 ft/yr of eroding.
Not this whole stretch, just Nantucket itself: the Coastal Change Hazards Portal is USGS's own live version of this data.