Eoearth says it's Oklahoma that has that honor.
Oklahoma is NOT a country.
Related: Are there ever Tornados in Poland?
I wondered,because I never heard 0f any hitting Poland
Rarely, however last year poland had 3 tornados en.wikipedia.org/wiki/Tornadoes_of_2007 (click edit > search > type in poland)
v. rare occurrence. I remember the one in Częstochowa, dated July 20