There are airshows in other countries. http://en.wikipedia.org/wiki/Ramstein_airshow_disaster (might even count as US ground as it was a US military base).

The last 2 years I went to Osh Kosh (2006 and 2008) there were two fatalities - one when a visiting pilot crashed on his way in (a lot of people fly in and camp at the air show) and another when two reno air race plans doing a race demo collided on the way in for landing. The sad part about the later crash is that it was a father and son who collided and the son was the one who died.

The president of the International Council of Air Shows made a PR-effective statement. However, looking into the history of airshows makes them look rather dangerous. (http://en.wikipedia.org/wiki/List_of_airshow_accidents)

1952? No way, I remember one where a jet hit the runway and a fireball engulfed the crowd that occurred probably in the late 1980s.

I think after that crash aircraft were banned from flying towards or over spectators the planes had to fly parallel or away from the crowd.

Yes and we can also use common sense to know an 80 year old dude flying a highly modified racing plane right above spectators is spectacularly stupid.

The other ones were deaths of participants rather than spectators though.

If there's very rarely any fatalities, or even injuries, amongst the millions of people who go to airshows every year (the attendance at EAA AirVenture Oshkosh is around 800,000 every year for example, and Paris Airshow is around 350,000 people, plus the hundreds if not thousands of airshows like this one in Reno), how is it particularly risky?

So quite safe relative to the risk of driving to the airshow?