To the untrained eye, it seemed that prior to the 1920s there were few noteworthy American boxers of Italian origin and only a limited presence in the decades that followed. But behind many Irish boxing names there frequently stood an olive-skinned, dark-haired battler with a hidden identity. More than one thousand Italian professional boxers went by Irish pseudonyms.
Italian immigrants entered boxing at a time when the booming American economy took advantage of Italian muscle to fuel the nation's growth. However, the ruling elites – the very ones who benefited from cheap labor – disparaged Italians, describing them as "biologically incapable" and a "burden on America."
Source: http://www.irishcentral.com/