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There are multiple copies of the same map in your Historical Topographic Map Collection that all have the same date. Is there a difference between those maps?

Two or more historical topographic maps with the same date typically result from revisions and reprints. The differences are often minor.

The date used to identify a map is in the lower right corner. If there are multiple editions with the same compilation date, look for additional dates in the lower right portion of the map collar that might differentiate them:

  • Date on Map -- The year of base compilation, or the year of a significant revision
  • Imprint Year -- The year the map was printed
  • Photo Inspection Year -- The year when a photo inspection was last done on the map
  • Photo Revision Year -- The year when photos were used to revise a map
  • Field Check Year -- The year map content was verified in the field
  • Survey Year -- The year when a field survey was completed for the mapped area
  • Edit Year -- The year the map was last globally edited or revised

Learn more: Historical Topographic Maps - Preserving the Past