United States: population dynamics in the face of structural change

The United States of America remains the third most populous country in the world after India and China. Since independence, it has undergone a remarkable demographic expansion, with immigration as the main driving force. However, for a long time, the natural balance has been strongly in surplus, thanks in particular to a higher fertility rate than in other Western countries. Since the 2000s, however, the population and geography of the United States have undergone significant change. To assess this, we need to answer the following questions: Why is the natural balance in the United States weakening in an unprecedented way? What structural changes are taking place in the geography of the countries of origin of immigration? How is the spatial distribution of the population between U.S. states being profoundly altered?