American smokers will no doubt have noticed by now that every pack of cigarettes sold comes emblazoned, somewhere, with the cryptic little motto: "20 Class A Cigarettes". It's not hard to imagine that if there are Class A cigarettes, somewhere there are also Class B cigarettes. However, there are not; or rather, there are notional Class B cigarettes, but none in actual existence.

My first thought on this was that the classes were some kind of measures of quality; something like FDA grading for meat. Of course this isn't the case - even the super-extra-more-discount-than-Dorals cigarettes that are only available in off-brand gas stations in the bad part of town, the kind that are probably made from coal mine tailings mixed with whatever they sweep off the floor in the factories where they make major brand cigarettes - even these are Class A.

The truth is that the classes are a measure of weight, which determines how much tax is due on them, and Class B cigarettes are the heavier ones. So heavy, in fact, that for cigarettes to qualify as Class B, they'd have to be six or seven inches long, or almost as wide around as they are long. Neither of which is a particularly appealing quality in a cigarette. So unappealing, in fact, that nobody makes them anymore.

One more prosaic answer to one of life's little mysteries.