But as obvious as their presence might have been, Jewish crime remained a hushed subject in the history of Jews in the U.S. This oversight was intentional and by no means an evidence of lack of criminal activities in Jewish circles. In fact it was the nefarious activities of Jewish entrepreneur Joseph Seligman that led to the stock market crash in late 1800s as Ginsberg notes:

"[the crash] ruined thousands of investors, implicated President Grant, and led to a Congressional investigation of [Jay] Gould and Seligman ... Similarly, in the early 1890s, Jacob Schiff collaborated with E.H. Harriman in the latter's attempts to wrest control of the Northern Pacific Railroad from J.P. Morgan and James Hill ... When the price of the Northern Pacific Stock collapsed, the entire market crashed in the notorious 'Black Thursday' panic that led to a nationwide economic depression." [Ginsberg., p. 73]

Thus Jewish organized crime was certainly not limited to narcotics or for that matter the unions. It was much wider...

They were also widely spread across the U.S. And had significant presence in some of the biggest urban centers of the country including Chicago, Cleveland, Detroit and New York. Though in competition with the Italian mafia, there were some areas where they worked in collaboration with Italian gangsters but in short, Jewish organized crime was as much a reality as Irish or Italian mafia. It was however hushed down over the decades to show that such instances of crime were only a minor deviation from the norm in Jewish history.
References

Ginsberg, Benjamin. The Fatal Embrace: Jews and the State. The University of Chicago Press, Chicago and London, 1994.

Silberman, Laurence J. Mapping Jewish Identities. New York University Press, New York & London, 2000

Katcher, Leo (1959/1994). The Big Bankroll. The Life and Times of Arnold Rothstein, New York: Da Capo Press