The Massachusetts Office of Coastal Zone Management launched the Shoreline Change Project in 1989 to identify erosion-prone areas of the coast by compiling a database of historical (mid 1800's-1989) shoreline positions. Trends of shoreline position over long and short-term timescales provide information to landowners, managers, and potential buyers about possible future impacts to coastal resources and infrastructure. In 2001, a 1994 shoreline was added to calculate both long- and short-term shoreline change rates at 40-meter intervals along ocean-facing sections of the Massachusetts coast. In the 2013 update, two oceanfront shorelines for Massachusetts were added using 2008-2009 color aerial orthoimagery and 2007 topographic lidar datasets obtained from NOAA's Ocean Service, Coastal Services Center. In the 2018 update, two new mean high water (MHW) shorelines for the Massachusetts coast extracted from lidar data between 2010-2014 were added to the dataset. This 2021 update includes one new shoreline extracted from lidar data collected in 2018 by the U.S. Army Corps of Engineers (USACE) Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX). This new shoreline was extracted for the North Shore, South Shore, Cape Cod Bay, Outer Cape, South Cape, Nantucket, Martha’s Vineyard, and a small portion Buzzard’s Bay. 2018 Lidar data was not available for Boston or the Elizabeth Islands region. This new shoreline was extracted from the lidar survey using either a profile method or contour method, depending on the location of the shoreline. This data release also includes a compilation of previously published historical shoreline positions spanning 170 years (1844 to 2014), intended to be used as an authoritative shoreline database for the state. This data is an update to the Massachusetts Office of Coastal Zone Management Shoreline Change Project.