Data layers in this child item include high-water mark and storm-sensor data collected by the U.S. Geological Survey (USGS) New England Water Science Center following the January 4, 2018, and March 2-4, 2018, winter-storm events in New England. High-water marks and continuous water-level sensor data range from Portland, Maine, to Provincetown, Massachusetts, and reference the North American Vertical Datum of 1988 (NAVD88). For more information about these storm events and the data collection, please see Bent, G.C., and Taylor, N.J., 2020, Total water level data from the January and March 2018 nor’easters for coastal areas of New England: U.S. Geological Survey Scientific Investigations Report 2020–5048, 47 p., accessed June 3, 2021, at https://doi.org/10.3133/sir20205048 Flood-inundation map layers and interim products used to create them also are included in this child item. The USGS polygon of the stillwater-inundation map reflects a statistical storm with a 1-percent annual exceedance probability from Portland, Maine, to Provincetown, Massachusetts, based on coastal tide-gage data. The January and March 2018 inundation maps are polygon shapefiles of estimated flood extent derived from the high-water mark and storm-sensor data following the storm events. The flood extents and water-surface elevations were derived from simplified estimations of high-water mark and storm-sensor data and delineated using 2-meter-resolution lidar digital-elevation models. Interim data layers that were used to create the flood-inundation polygons include a coastal flood-profile line and coastal watershed boundaries. The compressed zip files contain ESRI shapefiles that include xml metadata files. Detailed processing steps are documented in the metadata for each layer. See the Scientific Investigation Report associated with this data release for more information.