Lynn, MA Coastal Erosion Rate
Is the coast eroding 2 miles southeast of Lynn, MA?
Good news, and an honest one: USGS's data can't distinguish this stretch, 2 miles southeast of Lynn, MA, from a flat trend. Whatever small movement it measured here is statistical noise, not a reliable direction, so none is claimed.
What this reading actually covers
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 Lynn, MA, rather than showing one arbitrary line. Segment center: 42.45, -70.94. 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
60 transects feed this segment's number; 53% of them individually measured retreat. USGS's confidence interval here is ±0.21 ft/yr. The unadjusted figure here, -0.01 ft/yr, would place it 758 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. Rank 1200 nationally for growth belongs to Tokeland, WA, 2581 miles from this stretch, measured at 5.19 ft/yr. 2.4 miles away, Swampscott, MA is the nearest other measured stretch: also no significant trend.
Not this whole stretch, just Lynn itself: the Coastal Change Hazards Portal is USGS's own live version of this data.