What are the factors causing Americas population to grow?
A There are only four factor that cause America’s–or any nation’s–population to change: Births, deaths, inward migration, and outward migration. If birth exceed deaths and if inward migration exceeds outward migration, a nation’s population grows. During some periods America’s population growth has been caused primarily by births exceeding deaths. More recently, America’s population growth is caused primarily by inward migration exceeding outward migration and by greater than replacement fertility among some inward migrants and their children.