That is impossible to determine. The United States averages over 1000 tornadoes every year, many of them occurred before we started keeping records of them.
There has been a record number of tornadoes that is changing very quickly. That is why this answer is just from before today. There may be more today. The date is 5-27-08 and according to the Storm Prediction Center there have been 1191 tornadoes in the US this year.
Yes, though technically they are not tornadoes.
There have been many thousands of tornadoes in the United states. This country averages over 1000 tornadoes every year.
In 2011 there were 1,626 tornadoes and 552 deaths.
There were 1692 tornadoes in the U.S. in 2008.
No, tornadoes have been recorded on every continent except Antarctica. But usually, the US is the most common place for tornadoes, especially in Tornado Alley.
There were 1,103 tornadoes in the U.S. in 2006.
There were 1265 confirmed tornadoes in the U.S. in 2005.
There were 1159 confirmed tornadoes in the U.S. in 2009.
1098 tornadoes were confirmed in the U.S. in 2007.
There were 1132 recorded tornadoes in the U.S. in 1991.
There were 1297 recorded tornadoes in the U.S. in 1992.