With the young age of the population at that time (the US was still an emerging market, ) and additional culling of the population by World War II, not many people tapped into the social security system.

FORBES: The Fallacy Of Saving For Traditional Retirement

Puerto Ricans have been migrating to the United States since the 1800s, but it wasn't until World War II that this population movement peaked.

CNN: Commentary: Sotomayor as American as mango pie

Kansas City is one of only 15 cities with a population of at least 200, 000 in 1950 that saw substantial population losses since World War II but have rebounded in recent years, according to an analysis of U.S. Census Bureau data by Jordan Rappaport, an economist at the Federal Reserve Bank of Kansas City.

FORBES: America's Comeback Capitals