The last reported case was in East Africa somewhere, back in the 70s.
It only survives in laboratories - somebody in England caught it in a lab later - most stocks have been destroyed (although I don't know if I trust the CDC given their foolishness over ebola . . . and who knows what the Russians are up to?)
Do you know something I don't know?
It is easy to imagine a terrorist finding the grave of someone who died of smallpox, exhuming the body, infecting someone, perhaps himself, with the virus, and taking a tour of major world airports.
It is also easy to imagine the body of someone who died of smallpox becoming disinterred by some natural phenomenon, e.g. hurricane, earthquake, etc. Bodies in North Carolina were disinterred by one of the hurricanes in recent history.
Smallpox would sweep through an unvaccinated population fast.