Don't you think that in order to stop ALL undocumented immigration into the U. S. from third world countries like Mexico, El Salvador, Guatemala, etc, etc their countries would first need to have an economy as good as ours??

Most of the undocumented immigrats come to work. There sure is a number that came for other reasons, but they mainly came to work. Perhaps if their homeland gave them work, they would not need to come here.