The map above color-codes counties by when they hit peak population, from 1920–2015. Also, all population peaks in 1920 or earlier are color-coded identically, in the very lightest tan shade.
Population decline has occurred in the majority of U.S. counties, and those declined counties included over half the population of the United States 60 years ago. Today, fully a quarter of Americans live in counties below their peak population. However, that number can exaggerate the prevalence of ongoing decline: only 396 counties hit their minimum population in 2015, and they accounted for just 4 million people in 2015, versus about 7 million in 1940: from 5.3% of the nation to 1.3%.
Population decline has been concentrated in small, rural counties, former coal-producing areas, and urban centers. Of those categories, urban centers have shown some recent strength in some cases, while rural areas and coal-counties have been far less likely to show any sign of recovery.
