A view of the Northern end of the city of San Francisco. On the left, a map based on an 1852 coast survey.On the right, a present-day view of the city.
With over half of the U.S. population living in coastal areas, it's no wonder that our shorelines have dramatically changed over time. Now, with NOAA's new Historical Shoreline Survey Viewer, it's easy to access a large number of historical shoreline surveys conducted by NOAA and its predecessor organizations.
About 7,800 surveys—the earliest dating back to 1841—are available for viewing in Google Earth. In addition to overlaying a scanned image of the survey in Google Earth, the Viewer provides links to download: the original scan and metadata, the resulting extracted vector shoreline, and a descriptive report compiled by the survey team.
Shoreline surveys refer to topographic sheets compiled from maps derived in the field with a plane table, in the office from aerial photos, or a combination of the two methods. These shoreline surveys are the authoritative definition of the U.S. high-water line and may also include details such as roads, prominent buildings, and other features along the coast. The surveys were used as base maps to construct nautical charts primarily used for navigation.