Use shared context
Record the team and years you worked together. Prefer a public professional route over a private address. Watch for similar names and old profiles that no longer describe a current role.
Ask an intermediary
A mutual colleague or alumni group may forward a message. Let them make an introduction without requesting private contact details. Explain your purpose plainly and allow them to decline.
Keep the note short
Identify yourself and the connection, then make a low-pressure invitation. Avoid sensitive workplace material or private stories about other colleagues. Accept a refusal without trying another route.
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.