Historians who wrote during the turn of the twentieth century tended to focus on political and military events and themes, while historians who wrote during the middle- to late-twentieth century tended to focus on

They were eliminating problems caused by industrialization, urbanization, immigration, and corruption in government

Be the economy is horrible so people immigrate to the usa for a better life. most people just grow up from poverty and work day and night to support their family, some just come because there is a lot of drug dealers and gang that assaults people.