Answer:
A pull factor to immigrate to the United States.
Step-by-step explanation:
The United States Economy grew very fast during the late nineteenth century. The country had left behind the Civil War, and the industrial revolution took full force in the territory, specially in large cities like New York, Philadelphia and Chicago.
This provided Southern and Eastern Europeans a pull factor to immigrate to the U.S. Hundreds of thousands of Italians, Polish and Jews, mainly from Poland itself, and also from the Russian Empire, emigrated to the United States during this time.
They were looking for better economic opportunities, because while the U.S. economy was growing fast, the economies of Southern and Eastern Europe were lagging behind, since in most of these countries, industry was still non-existent.