I recently bought a stamp that I've been looking for, for a very long time. It appears that the online seller wasn't aware of the significance of the "export" text on this particular example, as there was no mention of it in the lot description.
Meat inspection stamps range from fairly common to very rare, depending on a number of factors, such as who printed them, their condition, and various other varieties.
From my experience, the stamps that were used only on meat that was exported from the U. S. are the rarest types. But there is a provisional type of the 1906 regular meat inspection stamps that is also quite rare. I'm guessing that not that much meat was sent overseas in the 1890s from the U. S., considering how long sailing times were and that most ships didn't have refrigeration. But maybe they used ice?

I asked Eric Jackson about this stamp, and this is what he said:
Quote:
This is only the second example I have seen. I had one probably 35 years ago.
The following information comes from the introduction that I wrote about these stamps in one of my books:
Meat inspection stamps were in use from March 3, 1891 until about 1908. If the meat was shipped out of the slaughterhouse as an entire carcass, then tags were attached to it. Most meat however was shipped out as individual pieces and was thus packaged in cardboard or wooden crates. The stamps were applied to the outside of these containers.
All stamps were to be cancelled with five parallel waved lines, the inspection date, and the inspector's name (the official abattoir number replaced the inspector's name in 1895). Most of the earliest stamps were first applied to the container with paste or glue, and then with five tacks or staples, one at each corner and one in the center, and finally a coating of varnish was applied over the stamp. Further, the stamps were to be obliterated from the container once the contents were removed.
As a result of these requirements, virtually all early meat inspection stamps are today not only uncommon but are usually found in poor condition. Thins, tears, and even pieces missing are the norm for these stamps. Meat inspection stamps in fault-free, very fine condition are highly prized and sell for a premium over the values shown here.
(The condition of the stamp shown here is remarkable; even with the obvious small faults its overall condition is excellent.)
All of the Act of 1891 meat inspection stamps were supplied in vertical panes of five, with a stub at the left of each stamp. This stub was retained by the abattoir's inspector. The top stamps in the pane were imperforate at the top, while the bottom stamps in each pane were imperforate at the bottom. All stamps in the pane were imperforate at the right. The inspectors were veterinarians that were paid for their services; the stamps were essentially the slaughterhouse's receipt to the customer that their product had, indeed, been inspected.
Oleomargarine was originally manufactured using beef tallow. Packages of oleomargarine thus had to have a meat inspection stamp as well as an oleomargarine stamp attached to them. This usage probably accounts for how the majority of meat inspection stamps were used.
The 1906 meat inspection act was a result of the publication in 1906 by Upton Sinclair of the book
The Jungle. Sinclair's novel was fiction, but it raised an awareness by the public of the not-always-hygienic procedures that were used by the meat butchering and meat packing industry. The heightened public awareness of the butchering industry eventually led to considerable reform of the then-current health and sanitation practices. The 1906 meat inspection stamps were only in use for a year or so, and are today fairly rare.
This is an example of a typical use of these meat inspection labels:

Jim