Respuesta :
The industrial revolution. There was now an excess amount of product and people started having less kids however, those kids survived.
Answer:
Various factors are contributing to the rise of the population of the United States :
a) There was a large population of young Americans who were starting families.
b) There as a decline in mortality rate, thus further boosting the population.
c) The area was expanding as new states were merging, providing enough space for the growth of population.