I started this map with the 1901 topographical map of the County. You can view and download historical topo maps here: https://ngmdb.usgs.gov/topoview/
Layered on top of that, I obtained bathymetric data and side-scan sonar imagery from data collected by the MD Department of Natural Resources circa 2014. Those layers are about 75% transparent so you can see both the existing and new features underneath.
I also added modern-day roads from Maryland’s GIS download and current property development subdivisions as derived from the state’s Department of Assessment and Taxation parcel GIS products. I also added public and quasi-public land from my Ultimate map series. This layer was also developed from the MDAT GIS products, but takes some analysis to develop into a workable layer.