There's a good book that covers this exact topic in much more depth. It's called "False Economy: A Surprising Economic History of the Word" by Alan Beattie. If I remember correctly, he focuses on how Argentinian land was owned by wealthy elites, satisfied with their wealth. In the US, small parcels of land were handed out to poorer individuals. Thus, the US held a greater attraction for immigrants. In the US immigrants also migrated inland quickly, leaving room in the cities for more immigrants to arrive.

Some of the book is available online through google books.