Minneapolis’s Star-Tribune reveals that the US Army Corps of Engineers owns an album of Henry Peter Bosse’s photographs that was just appraised at $4.5m. Bosse was the bard of the Mississippi river’s transformation from wild river to commercial super-highway. His work is rare and the Corps of Engineers learned 20 years ago that the album—which was sitting in the captain’s desk of a river dredge for 50 years—was worth $1m. They put it in a vault for safe-keeping.

Since quadrupling in value, the Corps is looking for a way to put the book on display for the public. The startling price brings to mind where other examples of the photographer’s work might be:

The Mayo Clinic Foundation has one, as does a steamboat museum in Dubuque, Iowa. When an antique dealer on the East Coast sold one for $66,000 in 1990, the world rediscovered the Prussian draftsman and his keen eye.

Anfinson, then working for the Corps of Engineers, did some research and learned that one of the Bosse albums had been given to the dredge William A. Thompson at its christening in 1937. Thompson, a Corps engineer who died in 1925, had worked alongside Bosse. Although no one’s sure, their widows might have been behind the album-to-dredge donation.

Anfinson called the dredge, which was working on the river near St. Louis, and asked: “Do we have a book of blue photographs?”

Yep. They’d been sitting on the captain’s desk from 1937 to 1989. With no stains from coffee cups, odds are no one pulled it out much. Once the dredge returned upriver to St. Paul, Anfinson snatched up the book and put it in the vault. It was appraised then at $1 million and has quadrupled in value in the 20 years since.

Locked in St. Paul vault: $4.5 million photo album (Star-Tribune)