Although Oliver Twist takes place in England, it gives us insight into conditions there that led people to go to America.
In the 19th and 20th century, America saw an influx of immigrants. As we see from this book, things in Europe were difficult for the poor. There were few opportunities, and no room to grow. In the early 1800’s a person could immigrate to America and get some land on a homestead for free. Working the land was the only purchase power you needed. You can see how the offer would be attractive to Europeans who were used to cramped and unsanitary conditions.
England had a variety of attempts at taking care of the poor. The Poor Law and workhouse system were not the best way to do it, as Dickens so cheekily tells us.
So, they established the rule, that all poor people should have the alternative (for they would compel nobody, not they), of being starved by a gradual process in the house, or by a quick one out of it. (ch 2)
In the end, conditions were not often better in the factories of American cities than they were in England, but you can see why so many people immigrated to the land of opportunity.