Because the Jews and Christians where allowed to serve in the government.
The past war crash in america occured after WW1 as the result of high inventories of manufactored goods with no local buyers and a drop-off in exports, and falling prices for farm produce
As described in NewsRepulic, During the Guided age, as defined by author Mark Twain, during the 1870's in big cities, like Boston, Chicago, New York, Cleveland, corruption was prevalent. The new immigrants, who were mainly looked upon as the least employable, the bottom of the social status, and of little value. They were someone who is new to the country, lacking in language skills, and someone who has come here to take your job. So, for them to assimilate, to survive, many immigrants were forced to join together to provide support the local political bosses. In exchange for their loyalty and votes, the new immigrants were provided, a chance for jobs, housing, help in naturalization, business licenses, assistance in the courts and a voice in the community.
The domestic manufacture of new machine guns that civilians could purchase was effectively banned by language in the Firearm Owners Protection Act of 1986 (also known as "McClure-Volkmer"). The language was added in an amendment from William J. Hughes and referred to as the Hughes Amendment.
