Here's a chart that tells you pretty much all you need to know about America's decline:
In the 1950s and 1960s, when government's payments to individuals were under 30% of government spending, we built an interstate highway system, went to the Moon, and built a military so strong that it deterred an aggressive totalitarian Soviety Union for half a century and, ultimately, caused that dictatorship to collapse.
Today, when we are spending 70% of our government's total spending on direct transfer payments does anyone think that our federal government could rebuild the highway system? Could go to the Moon, or Mars? Does anyone think that our military is strong enough to counter Russian aggression in the Crimea? (Another topic: to me, that would be a bad idea anyway, but it's moot, because we lack the strength.)
Put differently, in the 1950s and 1960s we were a country that built things that added to our national wealth. Today we are a country of consumers.