Why, on the whole earth, do the UFOs only visit America?
First of all, let me reiterate the point made here. There has never been any reliable evidence of any kind to suggest that alien spacecraft have visited Earth.
But that's not to say that people haven't looked at the claims of UFO sightings scientifically. In particular, the distribution of UFO sightings across the globe might be of interest. The best resource I've found on this subject is this page. According to the statistics compiled on that site, the United States has the most sightings of any single country, followed by France and Great Britain. (Though I haven't looked at it carefully enough to pick out the countries with the most sightings per capita.)
I think the most interesting map on that site is the distribution of sightings in Europe. France and Great Britain have many more sightings than Germany, even though Germany has a larger population than either of those two countries. You can find similar discrepancies all over the world. There's more than one way to interpret data like this. But to me, it seems a little far-fetched that aliens would recognize national borders, and visit one country much more than another if the two countries are geographically close, and similar in population, population density, and economic development. So a map like this suggests to me that UFO sightings are likely to be a cultural phenomenon.
This page was last updated June 27, 2015.