The U.S. is no stranger to tropical systems, but the run that we have had with no major land falling hurricanes is nearly unprecedented. It has been over 9 years since the last major hurricane, category 3 or stronger, has made landfall in the United States. I don't want to downplay the destruction created by Sandy in 2012 and Ike in 2008, but under the Saffir-Simpson scale guidelines (the scale we use to measure hurricane strength by sustained wind speeds and pressure), they were not major hurricanes.
Hurricane Wilma: the last major hurricane to make a U.S. landfall
Since the record setting year of 2005 where 4 major hurricanes came ashore (Dennis, Katrina, Rita, & Wilma), the truly monstrous storms have missed the U.S. coast. Wilma was the last of these Texas sized storms to make landfall with 120mph sustained winds in southwest Florida. Since then, not a single major hurricane has reached the U.S. which is the longest such streak since records began back in 1851.
The busy season of 2005 with 4 major hurricane U.S. landfalls
So what is causing this streak and is it truly that unusual? NASA researchers at the Goddard Institute for Space Studies put together a statistical model that shows that a streak like this occurs roughly every 177 years. But these scientists can't really conclude as to why. In fact, their conclusion is there really is no one reason why this would happen, it appears to be sheer luck, or coincidence if you prefer.
Every tropical system in the Atlantic since the last major landfalling hurricane
Overall hurricanes have stayed pretty constant and right around normal since 2005 with major hurricanes staying pretty constant as well. In fact, while the U.S. has had no major land falling hurricanes, Cuba has seen 5 since Wilma in 2005. Water temperature fluctuations don't appear to have too much to do with it either since years with slightly cooler temperatures have had just as many or more major hurricanes, and vice versa. While certain weather patterns like La Nina make it more conducive for tropical development, it doesn't necessarily mean it will happen. So there doesn't appear to be any specific type of weather pattern that is shielding the U.S.
Now we are headed into an El Nino year, which is historically unfavorable for tropical development, so we shall see if we can get through another season without a major hurricane impacting America. But remember, it doesn't even take "the big one" to cause extensive damage and loss of life..