How Speedy Was the Mail?

Ever wonder how fast the mail was one hundred years ago? There was a slight clue in an old pension file:

• Letter dated 3 May 1907, Washington, DC–sent to West Point, Illinois.
• Response to letter is dated 7 May 1907, West Point, Illinois.
• Response received 9 May 1907, Washington DC.

The letter was a request for information in a pension file. There’s no guarantee of when anything was mailed and a date could easily be off, but the timeline was tighter than I thought it might be for 1907.

Just something to think about. Are there clues about the speed of mail in an old record you have?