To quantify rates of change (erosion or accretion) along coastal and estuarine shorelines in Maryland, the Maryland Geological Survey (MGS), and the U.S. Geological Survey (USGS), installed and ran a computer program, the Digital Shoreline Analysis System (DSAS), using as input a series of digital shoreline vectors dating from 1841-1995. Shorelines were derived from three sources: (1) maps from a Historical Shorelines and Erosion Rates Atlas (Conkwright, 1975), (2) Coastal Survey maps (topographic or T-sheets) produced by the National Ocean Service (NOS), a branch of the National Oceanic and Atmospheric Administration (NOAA), and (3) a digital wetlands delineation based on photo interpretation of digital orthophoto quarter quads. DSAS constructed a “baseline” landward of and approximately parallel to the shorelines, inserted nodes every 20 m along the baseline, and cast straight-line transects from each node, perpendicular to the baseline, across the shorelines. Based on the time elapsed and the along-transect distance between shoreline pairs, DSAS calculated rates of change for each transect. Subsequently, updates began in 2015 is updating by county the DSAS process using newer Shoreline data and refined calculations to update the Rates of Change erosion values by county. Currently Anne Arundel, Baltimore, Calvert, Harford and Prince George's counties have the newest erosion rate values contained in this Data set.