1915 Panama-Pacific So-Called Dollars: Reading HK Numbers and Rarity Ratings

Why Was There a Fair in San Francisco in 1915?

Officially, to celebrate the opening of the Panama Canal, completed in 1914 and one of the largest engineering achievements attempted to that date. The canal transformed the economics of Pacific shipping, and a Pacific-coast city had an obvious claim to mark it.

Unofficially, and more importantly to the people who built it, to demonstrate that San Francisco had come back. The 1906 earthquake and the fire that followed destroyed a large part of the city and killed thousands. Nine years later the exposition was a deliberate statement of recovery, staged on reclaimed ground at the northern edge of the city.

That double purpose gives the material a particular character. It is celebratory in an assertive, slightly defiant register, and it was produced by a city with something to prove.

The Palace of Fine Arts, built for the fair, still stands — the only major structure to survive, and the reason the exposition remains physically present in San Francisco rather than only in its souvenirs.

How Do HK Numbers Work?

HK refers to Harold Hibler and Charles Kappen, whose 1963 reference *So-Called Dollars* catalogued dollar-sized commemorative medals and tokens and assigned the numbering the field still uses.

An HK number identifies a design. It does not identify a metal, a grade or a specific specimen. This is the single most common source of confusion in listings, and it works exactly as DeWitt numbers do for campaign medals — a point we cover in why one campaign medal exists in several metals.

Alongside the number, Hibler and Kappen assigned a rarity rating on a scale from R1 to R10:

R1 to R2 indicates common material you can find whenever you want it. R3 to R4 indicates moderate scarcity. R5 and above indicates genuine scarcity — a piece that requires waiting for. R8 to R10 covers the extremely rare through to unique.

Our archive spans this range: the Oregon HK 411 at R3 sits in the moderate band, while HK 404 in bronze and HK 414 in gilt brass are both R5.

What Are the State Issues?

Several US states sponsored buildings and exhibits at the exposition, and a number issued their own so-called dollars — pieces identifying a specific state's participation rather than the fair generally.

This creates one of the most satisfying sub-collections in the field: a run of state issues from a single exposition. The unifying element is the fair; the variable is the state, and each piece carries its own iconography.

Our archive includes the Arkansas issue, HK 403, at NGC MS62 and the Oregon issue, HK 411, at MS63.

State issues also tend to attract regional collectors — someone in Arkansas who collects Arkansas — which supports prices independently of the exposition collector base. That is a genuine structural advantage over generic souvenir material.

How Much Does Metal Change Things?

Enough that metal should always be established before price is discussed.

The 1915 series was struck across bronze, gilt brass, silver and other alloys depending on the issue. A single HK number can therefore describe several genuinely different collectables with different survival rates and different prices.

Gilt brass is the metal that causes the most trouble. Gilding is a thin gold wash over a brass core, and it wears through on high points with handling. A gilt piece with most of its gilding intact is considerably more desirable than one worn down to the brass, and photographs disguise the difference easily — which is a strong argument for buying gilt material certified.

Bronze is more forgiving and ages predictably, developing a stable patina. As always, an original bronze surface beats a cleaned one regardless of technical grade.

What Does an AU Details Grade Tell You?

It tells you two separate things, and collectors routinely conflate them.

AU — About Uncirculated — describes the amount of wear: a piece with light friction on high points but most original surface intact.

Details means the grading service declined to assign a straight numerical grade because of a problem outside the wear scale — cleaning, damage, a repair, environmental effects, mounting. The service is saying: this is genuine, here is roughly its wear level, and here is why it does not get a number.

So a piece graded AU Details is authenticated, lightly worn, and carries a disclosed issue. On an R5 piece that combination is often the sensible buy, because scarcity governs at that rarity level and waiting for a problem-free example may mean waiting years.

The same logic applies across this catalogue, and we cover it in more depth in what a 'Details' grade means. The principle: on common material, buy the grade. On scarce material, buy the piece.

Why Is 1915 the Best Series to Learn On?

Because it has depth, documentation and a full range of difficulty in one place.

Depth: enough distinct designs that you can collect for years without exhausting it.

Documentation: the HK catalogue covers it thoroughly, so you can always establish what you are looking at.

Range: pieces at R1 through to genuine rarities, which means you can build a real collection at modest cost while learning what scarcity actually feels like in practice.

Certification: enough material has been submitted to NGC and PCGS that population data is meaningful, unlike thinner exposition fields.

A collector who works through the 1915 series properly comes out understanding HK numbering, rarity ratings, metal variation and details grading — which is most of what is needed to buy confidently anywhere else in exposition material. The wider map is in collecting American world's fair medals and tokens.

Frequently asked questions

What does HK stand for on a so-called dollar?

Hibler and Kappen, the authors of the 1963 reference So-Called Dollars, which catalogued this material and assigned the numbering still used universally. An HK number identifies a design, not a metal or a specific piece.

How rare is an R5 rating?

Genuinely scarce. On the Hibler and Kappen scale of R1 to R10, R5 sits in the band where you take a good example when one appears rather than holding out for a better one, because opportunities are infrequent.

Should I avoid a Details grade?

Not on scarce material. Details means the piece is genuine but has a disclosed problem outside the wear scale. On common pieces, hold out for a straight grade; on an R5 piece, a Details example is often the sensible purchase.

What was the Panama-Pacific Exposition celebrating?

Officially the opening of the Panama Canal, completed in 1914. Unofficially, San Francisco's recovery from the 1906 earthquake and fire — which is why the fair had such an assertive character.

What are the state issues?

So-called dollars sponsored by individual US states that participated in the exposition, identifying that state rather than the fair generally. They make a natural sub-collection and attract regional collectors as well as exposition specialists.

Why does gilt brass need extra care?

Because gilding is a thin gold wash over brass that wears through on high points, and photographs hide the difference between a fully gilt piece and a worn one. It is the metal where independent certification most repays the cost.