How many tornadoes hit the United States in an average year?

How to get close to this number

The explanation gives the mechanism, and the mechanism gives the scale: cold dry air off a mountain range meeting warm wet air off a warm sea, across a flat continental interior with nothing in between. That configuration exists almost nowhere else, which is why one country records more than the rest of the world combined.

The count is also a detection artefact in part. Tornadoes are recorded when someone sees one or radar catches it, and this country has the densest weather-radar coverage and the most storm spotters anywhere — so some of the gap between it and other countries is observation rather than meteorology.

That said, the geography is real and dominant. Comparable mid-latitude interiors exist in Argentina and Bangladesh and do produce tornadoes, but neither has the same combination of a north-south mountain barrier and a warm sea feeding moisture directly into the plain. The figure describes a landscape, not a climate.