In what ways was the huge migration into the United States part of a worldwide phenomenon? What were the "push" and "pull" factors that brought immigrants to the U. S.?

The migration into the United States of people throughout history is part of the world wide phenomena of migration because individuals entering the U. S. are coming from regions all over the world for a variety of reasons. Most of these immigrants are economic immigrants seeking employment and greater opportunities in an economy like the U. S. which is usually stronger than their home economy which is why they decide to leave. Also other immigrants are fleeing conflict, reuniting with family, seeking education, or other factors. In general migration is representative of a push and pull model because there are factors that push migrants to migrate elsewhere such as war, disease, a weak economy, etc. and there are factors which pull migrants to a place such as a stronger economy, increased security, or better opportunities to live better.