There are a number of websites that provide excellent access to digitized and born digital maps. Here are just a few:
The Office of Coast Survey's Historical Map & Chart Collection contains over 20,000 maps and charts from the late 1700s to present day. The Collection includes some of the nation's earliest nautical charts, hydrographic surveys, topographic surveys, geodetic surveys, city plans and Civil War battle maps.
To locate a map visit http://www.nauticalcharts.noaa.gov/csdl/ctp/abstract.htm