Longboat Key, FL Coastal Erosion Rate
Is the coast eroding 0.4 miles northeast of Longboat Key, FL?
The coast 0.4 miles northeast of Longboat Key, FL shows no statistically significant trend either way. USGS's transects measured a rate here, but it's smaller than the survey's own margin of error for this stretch, so calling it "eroding" or "growing" would overstate what the data actually shows.
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 Longboat Key, FL into one ~3.5-mile reading rather than picking a single arbitrary line to represent the area. Centered near 27.40°N, 82.64°W. The survey behind it runs to 2001, in USGS's Gulf of Mexico 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.
Where this fits nationally
This reading comes from 106 individual transects averaged together, 61% of which measured erosion rather than growth. The published margin on this reading runs ±0.66 ft/yr. Taken at face value, this segment's raw -0.08 ft/yr reading would land it 668 of 1211 nationally - a number worth ignoring, since it's statistical noise rather than a real trend. Source: USGS Open-File Report 2004-1089. For scale: Gearhart, OR, 2586 miles away, ranks 1187 of 1211 nationally for growth, 3.64 ft/yr. 2 miles away, Longboat Key, FL is the nearest other measured stretch: also no significant trend.
Longboat Key, FL on the source map: try the Coastal Change Hazards Portal, zoomable well past this page's ~3.5-mile grain.