Hampton Beach, NH Coastal Erosion Rate
What USGS measures 1.1 miles south of Hampton Beach, NH
Good news, and an honest one: USGS's data can't distinguish this stretch, 1.1 miles south of Hampton Beach, NH, 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 Hampton Beach, NH, rather than showing one arbitrary line. Segment center: 42.90, -70.82. 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.
How solid is this number
86 transects feed this segment's number; 6% of them individually measured retreat. Uncertainty on this specific number: 0.51 ft/yr either side. The unadjusted figure here, 0.16 ft/yr, would place it 896 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: San Buenaventura (Ventura), CA, 2647 miles away, ranks 1122 of 1211 nationally for growth, 1.19 ft/yr. 3.3 miles away, Salisbury, MA is the nearest other measured stretch: also no significant trend.
Not this whole stretch, just Hampton Beach itself: the Coastal Change Hazards Portal is USGS's own live version of this data.