What became of the Black Hand after 1915?
Mafia and the Black Hand
In 1909, when Giuseppe Morello, the leader of the most powerful Mafia gang in New York, was arrested in connection with counterfeiting, a series of Black Hand letters were found at his home.
Agent ""Flynn"" of the Secret Service described the way in which the Mafia leader used the letters, adding a slight twist to the more simplistic methods of lesser criminals:
A threatening letter is sent to a proposed victim. Immediately after the letter is delivered by the postman Morello just ‘happens’ to be in the vicinity of the victim to be, and ‘accidentally’ meets the receiver of the letter. The receiver knows of Morello’s close connections with Italian malefactors, and, the thing being fresh in mind, calls Morello’s attention to the letter. Morello takes the letter and reads it. He informs the receiver that victims are not killed off without ceremony and just for the sake of murder. The ‘Black-Hand’ chief himself declares he will locate the man who sent the letter, if such a thing is possible, the victim never suspecting that the letter is Morello’s own. Of course, the letter is never returned to the proposed victim. By this cunning procedure no evidence remains in the hand of the receiver of the letter should he wish to seek aid from the police.
The New York press often labelled Morello and his gang ‘The Leaders of the Black Hand’, when actually their main criminal activity was counterfeiting, but there are some connections that can be made. Some members of the Mafia gang were arrested in connection with extortion, kidnapping and bomb throwing, all typical Black Hand crimes. These incidents, however, were minor extensions of their much larger criminal activities. An argument that cannot be applied to most Black Hand offenders.
The trail left by the crime wave draws a picture of an unorganized body, with no central leadership or hierarchical structure. Practiced by individuals, small groups of criminals and sometimes more established larger gangs, they all worked without kneed of knowledge of other Black Handers. It was a phenomenon born of imported criminal practices and the unique immigrant situation at the time. Had the criminals been centrally controlled, then they might have been easier to suppress. The Black Hand phenomenon began to decline after 1915, mainly due to tougher sentencing, federal mail laws, and tighter immigration control."
https://www.gangrule.com/gangs/the-black-hand