Is that a real part of the history of U.S.A ?

It is definitely a real part of history...bill the butcher...tweed..all the gangs. ..were real people. Theres a documentary called "the real gangs of new york" that explains alot of the history of that period. Part of why i loved the movie was it was based on real people n events.

Some of the events and characters are based on real people and things that happened, though facts are changed and things fictionalized for the sake of entertainment. Things weren't quite this violent back then, for one. The gangs were more like political groups who kept their fighting limited to the polls, generally. They did get the persecution of the immigrating Irish portrayed well, though. The riots were real, though again not accurately portrayed. They were actually worse than the movie showed, but the real events didn't go well with the story. They were disgusting and racially driven, it wasn't just because people had to go to war, they were worried about freed slaves taking jobs, which led to an unknown amount of death.. So, it's a movie, not a documentary, but I think it sparks a lot of interest in the past.