1966 Rate of Natural Increase

In 1966, the world’s rate of natural increase (RNI)—the difference between birth rates and death rates, excluding migration—was at a historic high, estimated at around 2.1% per year. This rapid growth was driven by high fertility rates and declining mortality, especially in Asia, Africa, and Latin America. Africa had the highest RNI, often exceeding 2.5%, due to persistently high birth rates and improving healthcare reducing deaths. Asia’s RNI was also high, particularly in South and Southeast Asia, while East Asia (notably China and Japan) began to see declines due to early family planning efforts. Latin America’s RNI hovered around 2.5%, with countries like Mexico and Brazil experiencing population booms. In contrast, Europe’s RNI was much lower, often below 1%, as birth rates had already declined sharply after World War II, and death rates were low. North America’s RNI was moderate, around 1.2%, reflecting the tail end of the baby boom. Thus, while developing regions experienced explosive growth, developed countries saw much slower increases, setting the stage for widening demographic contrasts in the decades that followed.

Data from US Census International Database