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| The U.S. Coast Survey created highly detailed topographic maps beginning in 1834. These maps eventually became known as topographic sheets or "T-sheets." This is a collection of 1,887 topographic sheets dating from 1834 to 1911, courtesy of the NOAA Central Library in Silver Spring, Maryland. The sheets have been grouped by state and then ordered geographically along the coast. The digital files were created by scanning photographic negatives the original sheets and then inverting the images to a positive format. The negatives are gross reductions in size from the map originals. The collection was scanned at a resolution of 1200dpi. The variance in the quality of the images in this collection is a function of the condition of the photographic negatives from which they were derived. |
