What were the major causes for the decline of the u. s. economy during the 1970s?

First the capitalist world was in the great economic depression.
Second "decline” took place in the 1970s and 80s during which the international competitiveness of U.S. commodities and capital decreased drastically.
Third “decline” occurred during the recent financial crisis.
        
 
                                   Reasons Why

* first two “declines”, the United States entered a new stage of economic growth through reform and innovation. There are still lots of uncertainties whether the U.S. economy would be able to recover this time, but it seems certain that one, the United States has fallen from the peak of economic hegemony and it is unable to change the trend of plural development of the world economy in the 21st century even if its economy could resurge, and two, the U.S. economy remains strong and will witness a fairly long period of development in the wake of fresh scientific and technological revolution.

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