Well see I think the 1970s was a great time for American cinema..The Godfather, Taxi Driver and so on. The 1960s was weak. Transitional period.
The 60's gave us Dr. Stranglove...The Man Who shot Liberty Valance and several other classics. The 70's actually were better than the 60's, if you discount all the leftist counter culture pablum they put out.
Strangelove that is....
Balderdash! The '60s had some great films..."THE RUSSIANS ARE COMING,THE RUSSIANS ARE COMING", "THE PAWNBROKER",and "2001; A SPACE ODYESSEY"; to name but three.