An on-line exhibit on the Smithsonian National Postal Museum's website features interesting tidbits about the United States Postal Inspectors.
According to the site, "One of the most unusual postal inspector assignments was in the mid-twentieth century when individual inspectors were assigned to the White House. When the President left the White House, the assigned inspector traveled with him. Travel duties included overseeing the dispatch, delivery and protection of the President’s mail, using a specially-assigned White House mailbag (shown above).
Pictured here in 1937 is Postal Inspector Herbert G. Theurer who carried the Presidential mailbag to Galveston, Texas, where President Franklin Roosevelt was staying while on vacation and was enjoying some offshore fishing aboard the presidential yacht Potomac.
To visit "Postal Inspectors: The Silent Service," click here.