The U.S. population isn't growing as fast as experts thought, and fewer people appear to be moving to Southern states like Florida and Texas that have been top destinations in recent decades. Yet while population growth and mobility have slowed nationwide, the South remains the country's fastest-growing region, continuing a shift in the nation's political gravity to Southern states. These are among the trends revealed in the initial batch of 2020 census data released last week. After missing its Dec. 31, 2020, deadline, the embattled Census Bureau disclosed statewide population totals in Apri...