1918 Jenny Plate Block Value & Price Guide (2026)

Bureau of Engraving and Printing, Public Domain, via Wikimedia Commons

When William Robey bought the only known sheet of Inverted Jenny stamps in 1918, he paid $24 for 100 stamps. That sheet was eventually broken apart - but not completely. A few multi-stamp pieces survived intact, including the plate number block. That plate block - a group of stamps still attached with the printing plate number visible in the margin - is the single most valuable piece of U.S. philatelic material in private hands. It has sold for as much as $4.8 million.

Quick Value Summary


Item	1918 Jenny Invert Plate Block
Year	1918
Category	Stamps - U.S. Airmail Error
Denomination	24 cents per stamp
Configuration	Block of stamps with plate number in margin
Total Known	1 plate block survives
Notable Sales
2005 (block of four)	$2,700,000
2014 (plate block)	$2,970,000 (Siegel)
2014 (plate block, private)	~$4,800,000 (Mystic Stamp Co.)
Rarity	Unique - only one plate block exists

The Story

The Inverted Jenny is famous as a single stamp. But philatelists know that the most valuable configurations are multiples - stamps still connected as they came off the press. And the most valuable multiple of all is the plate block.

When stamps were printed in sheets, the plate number appeared in the margin. Collectors prize "plate blocks" - groups of stamps with that margin number attached - because they prove the stamps came directly from the original printing sheet, unbroken since 1918.

Colonel Edward H.R. Green, who purchased the entire Inverted Jenny sheet from dealer Eugene Klein in 1918, had the sheet broken into singles and blocks. He kept the plate number block for himself. After Green's death in 1936, the plate block passed through a series of owners, each paying more than the last.

In 2005, a block of four Inverted Jenny stamps (not the plate block) sold for $2,700,000 at Robert A. Siegel Auction. Then in 2014, the actual plate number block - the crown jewel - sold at Siegel for $2,970,000. Shortly after, Mystic Stamp Company reportedly acquired it in a private transaction described as "north of $4.8 million."

The plate block is currently held by Mystic Stamp Company and has been displayed at major philatelic exhibitions. It is considered the most important piece of U.S. airmail philately.

How to Identify It

What Is a Plate Block?

A plate block is a group of stamps still attached to each other and to the margin of the sheet that contains the plate number. For the Inverted Jenny, the plate number appears in the selvage (margin) of the original sheet of 100.

Key Visual Markers

Multiple stamps still connected (the Jenny plate block contains the plate number and attached stamps)
Each stamp: Red frame with "U.S. POSTAGE" at top, "24 CENTS 24" at bottom
Blue Curtiss JN-4 airplane printed upside down in the center of each stamp
Plate number visible in the margin - this is what distinguishes it from an ordinary block
Perforated edges (perf 11) between stamps; straight edges on the margin side

Don't Confuse With...

Individual Inverted Jenny stamps - Worth $126,000 to $2,006,000 each, but not a plate block. See our Inverted Jenny page →
Normal Jenny stamps (C3) - The airplane is right-side up. Worth $50 to $350.
2013 commemorative Inverted Jenny - A modern USPS reissue, not the 1918 original.
Blocks without plate numbers - A block of connected Inverted Jenny stamps without the plate number in the margin is still extraordinarily valuable (a block of four sold for $2.7 million) but is not the plate block.

Value History

The Jenny plate block is unique - there's only one. Its value is defined by what buyers have been willing to pay:

Year	Price	Context
1918	Part of $24 sheet	William Robey's original purchase
2005	$2,700,000	Block of four (not plate block) at Siegel
2014	$2,970,000	Plate block at Robert A. Siegel Auction
2014	~$4,800,000	Plate block, private sale to Mystic Stamp Co.

For context, individual Inverted Jenny singles have sold for up to $2,006,000 (November 2023). The plate block commands roughly double to triple that because of its unique status.

Other Jenny Blocks

Not all Jenny multiples are plate blocks. Various blocks of two, four, and larger configurations exist from the original sheet. A block of four without the plate number sold for $2,700,000 in 2005. Position matters - stamps from the edges and corners of the sheet are more desirable.

Authentication & Fakes

Is This Stamp Block at Risk of Forgery?

The Jenny plate block is unique and extensively documented. Its provenance is traceable from 1918 to the present day. Forging it would be essentially impossible - every expert in the field knows what it looks like and where it is.

However, individual Inverted Jenny stamps are occasionally faked (see our Inverted Jenny page for details on authentication). Anyone claiming to have "another" Jenny plate block is either confused or dishonest.

Professional Authentication

The plate block has been examined and authenticated by the leading philatelic experts and organizations, including the Philatelic Foundation and Robert A. Siegel Auction Galleries. Its provenance chain is one of the most thoroughly documented in all of philately.

Where to See It

The Jenny plate block is currently held by Mystic Stamp Company and has been exhibited at the World Stamp Show and other major philatelic events. Mystic occasionally displays it at their headquarters in Camden, New York.

The Smithsonian National Postal Museum in Washington, D.C. holds other Inverted Jenny material and has extensive exhibits on the stamp's history.

Common Questions

How much is the Jenny plate block worth?

The last known transaction valued it at approximately $4.8 million in a 2014 private sale to Mystic Stamp Company. Given that individual Inverted Jenny stamps have sold for over $2 million since then, the plate block's current value is likely higher.

What's the difference between the plate block and a regular Inverted Jenny?

A regular Inverted Jenny is a single stamp worth $126,000 to $2,006,000. The plate block is a group of stamps still attached to the sheet margin with the plate number - the most important surviving piece of the original sheet. It's unique and worth roughly $5 million or more.

How many Inverted Jenny blocks exist?

Several blocks of varying sizes were preserved when the original sheet was broken apart. The plate number block is unique - only one exists. Other blocks of two and four exist as well, each with its own provenance and value.

Can I buy the Jenny plate block?

Not unless Mystic Stamp Company decides to sell. It's been in their collection since 2014. When and if it returns to market, expect it to sell through Robert A. Siegel Auction Galleries, where most major Jenny transactions have occurred.

Is the plate block the most valuable U.S. stamp item?

It's among them. At ~$4.8 million, it's one of the most expensive pieces of U.S. philatelic material ever sold. The only items that might rival it are extraordinary one-of-a-kind covers or the complete Inverted Jenny sheet itself (which no longer exists as a single piece).