Why did Americans migrate westward after the Civil War?

Quite simply, after the civil war, the American economy developed greatly. At that time, the population in the eastern United States was developed, and there was less and less land to be developed, while more and more immigrants came to the United States. At this time, the western United States was still a wasteland, and only a few Indians lived there, so most of the American population began to migrate to the west. At that time, the American government also encouraged Americans to emigrate to the west. President Lincoln proposed laws to encourage Americans to explore the west. It was only at that time that the civil war broke out, so as soon as the civil war ended, Americans who urgently needed their own private land enthusiastically moved to the western United States to carry out the western development.