1820, the year after the industrial revolution, caused modern economic growth. Countries where the modern economic growth initiated at the early phase experienced a rapid increase in the standard of living. These countries became more prosperous at a higher rate relative to the countries where modern economic growth has yet to arrive.
Since the industrial revolution started in 1776 in the U.K after the invention of the steam engine, living standards in countries like the U.K, France, and Portugal increased more rapidly than the majority of countries globally. Hence, in 1820, the living standards in various places around the world were “more widely varying than” they are today.