Charlestown, RI Coastal Erosion Rate
What USGS measures 4.3 miles east of Charlestown, RI
Good news, and an honest one: USGS's data can't distinguish this stretch, 4.3 miles east of Charlestown, RI, from a flat trend. Whatever small movement it measured here is statistical noise, not a reliable direction, so none is claimed.
The grain of this number
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 Charlestown, RI, rather than showing one arbitrary line. Segment center: 41.38, -71.54. Survey years: 2007-2009, method LRR, from USGS's New England / Mid-Atlantic shoreline-change assessment. That's how current the data is here, real, but not a live feed, since a shoreline survey is a major undertaking, not an annual check-in.
How solid is this number
57 transects feed this segment's number; 86% of them individually measured retreat. The published margin on this reading runs ±0.32 ft/yr. The unadjusted figure here, -0.23 ft/yr, would place it 467 of 1211 if ranked directly - but an unreliable rank isn't a useful one, which is exactly why "no significant trend" is the headline instead. Source: USGS Open-File Report 2010-1119. For scale: Barview, OR, 2652 miles away, ranks 1169 of 1211 nationally for growth, 2.33 ft/yr. 1.3 miles away, Charlestown, RI is the nearest other measured stretch: also no significant trend.
Charlestown, RI on the source map: try the Coastal Change Hazards Portal, zoomable well past this page's ~3.5-mile grain.