Harry "Nig" Rosen was a Philadelphia mobster who was a major organized crime figure on the east coast with influence as far as Atlantic City, Baltimore and Washington, DC.
Succeeding Max "Boo Hoo" Hoff as the cities chief bootlegger during Prohibition, he was a member of the "Big Seven" aligned with the Philadelphia faction along with Waxey Gordon and Irving Blitz
, later attending the Atlantic City Conference
During the 1930s, he and Lansky worked on expanding drug trafficking operations in Mexico as an alternative to older routes such as Japan now closed with United States entry into the Second World War. By 1939, a lucrative heroin network had been established from drug traffickers based in Mexico City to major cities across the United States including New York, Philadelphia, Miami and Los Angeles as well as Havana, Cuba.
He and his lieutenant, driver and bodyguard William "Willie" Weisberg, were named as dominant racketeers involved in the numbers racket under testimony from police superintendent George F. Richardson during the Kefauver Committee in 1951
During the early 1950s, Rosen became partners with Gaetano "Tommy" Lucchese after buying the Sweet Valley Improvement Company which was used by the Lucchese crime family to ship out clothing out of New York's garment district