The real US temperature graph above (not to be confused with the fraudulent one generated by NCDC) shows pretty clearly that the US is on a 70 year warming and cooling cycle, and that there is no reason to believe global warming has affected the US in any way.
However, there is an interesting feature in the 1950s and 60s. Note that it was cooling, and there was very little year over year variability. That was the time when the USSA and USSR were blasting hundreds of nuclear weapons above ground. Imagine how much dust that put in the upper atmosphere.