Stay Gold, America
In a figurative sense, the American economy has enjoyed lots of low-hanging fruit since at least the seventeenth century, whether it be free land, lots of immigrant labor, or powerful new technologies.
Tyler Cowen • The Great Stagnation: How America Ate All The Low-Hanging Fruit of Modern History, Got Sick, and Will (Eventually) Feel Better: A Penguin eSpecial from Dutton
A lot of the growth of the United States, up through the 1970s or so, has been based on these three forms of low-hanging fruit. Each of them is pretty much gone today.