The Japanese are becoming older. Americans are also becoming older. Demographic stress in Japan, measured by the dependency ratio (DR), is currently about 0.64. In the immediate pre-WWII era it was even higher because Japan's total fertility rate (TFR) was in the 4 to 5 range. As the TFR began...

In this short note I simulate the DR under various conditions and make comparisons with the US. Japan has experienced a large increase in its DR because its fertility rate is low, its people are long lived and it has little immigration. Fertility is the largest of the contributors in Japan. If...