Explanation of more or less steady rate of growth in real income in many NICs and many of the poorest LDCs.

Taking a long view of the US and other developed economies, we see with certain exceptions a more-or-less steady rate of growth in real income over the last couple centuries. Elucidate and describes the mechanisms by which this has occurred, and contrast our experience with: a) the recent performance of many NICs (newly-industrializing-countries) in the last few decades; and b) the performance of many of the poorest LDCs (less-Developed-Countries).