"If you have an older population, of course you have more deaths," said Qian Cai, a University of Virginia demographer who studies population trends. "That doesn't mean the population is less healthy or less vital."
US deaths reach record as population grows, ages →
"The migrants tend to be younger. They are in the stage of raising families. So one migrant may bring one, two, three or more to the locality," Ms. Cai said.
Arlington County among fastest-growing in Virginia →