Number a working copy
Preserve the original and label positions on a copy. Record the proposed event and who identified it. Numbered positions let people compare suggestions without writing guessed names on the image.
Collect independent memories
Ask what people recognise before showing a completed name list. Note who supplied each identification and why. Preserve disagreements instead of deciding by majority vote.
Share a careful caption
Distinguish confirmed names from suggestions and ask before publishing details about living people. Include the source and permission conditions. A traceable partial caption is better than a complete invented one.
Further reading
For source material and collection context, visit Library of Congress: maps. Check the collection’s own scope and access instructions before relying on it.