Nantucket, MA Coastal Erosion Rate
Is the coast eroding 7.7 miles northeast of Nantucket, MA?
2 feet a year: that is the measured retreat rate USGS's transects show for the coast 7.7 miles northeast of Nantucket, MA, averaged across the full historical record surveyed here. At that rate, the shoreline has lost roughly 20 feet over the last decade.
The grain of this number
Nothing here is parcel-level. USGS's raw transects run every few hundred feet along the shore; this page averages the ones nearest Nantucket, MA into one ~3.5-mile reading rather than picking a single arbitrary line to represent the area. Centered near 41.37°N, 70.03°W. The survey behind it runs to 2007-2009, in USGS's New England / Mid-Atlantic assessment, using the LRR method. Shoreline surveys aren't repeated every year, so this is the most recent long-term measurement USGS has published for this coast, not a live reading.
25 years at this rate
If 2 ft/yr holds for the next 25 years, the coast 7.7 miles northeast of Nantucket, MA would retreat roughly 50 more feet, a projection, not a certainty: erosion rates shift with storms, sediment supply and any armoring built in the meantime.
Where this fits nationally
34 transects feed this segment's number; 100% of them individually measured retreat. Uncertainty on this specific number: 0.64 ft/yr either side. Among the 1211 US coastal segments with a measurable trend, this one ranks 135 for erosion, 1 being the fastest-retreating coast in the dataset. Source: USGS Open-File Report 2010-1119. For scale: Gilgo, NY, 181 miles away, ranks 95 of 1211 nationally for erosion, 3.01 ft/yr, 1.5x this stretch's rate. 1.1 miles away, Nantucket, MA is the nearest other measured stretch: moderate erosion at 1.95 ft/yr.
Nantucket, MA on the source map: try the Coastal Change Hazards Portal, zoomable well past this page's ~3.5-mile grain.