That would be where the passport was issued. Mine is from a U.S. Consulate.
And something else is goofy about it I see. It says "see page 51" because their is an amendment or other note to the passport. In a normal passport it should be only 25 pages long.
This was covered upthread. To recap:
- The passport office issues 52-page passports for frequent travelers.
- Page 51 is for endorsements, not amendments.
- What page 51 says is "The Bearer is the President of the United States." It's shown at the two-minute mark of the video.