The population of the United States has increased steadily by roughly 2.5 million people every year since World War II. Throughout prosperity and hard times, Americans continue to have families. Many of the country’s regions have expanded to accommodate this population increase. Some cities have grown faster than others as the result of being at the center of some important new technology or job market. There are some cities, however, which have experienced such severe hardship and decline that their populations have actually decreased significantly.