Conversation so far:
Did Frank Hague commit any questionable acts?
He relied on two ordinances of dubious constitutionality to muzzle critics.
Did he do anything illegal?
He was also able to avoid prosecution despite numerous federal and state investigations in part due to the fact he took most of his kickbacks in cash.
Did anyone attempt to prosecute him?
He was also able to avoid prosecution despite numerous federal and state investigations.

Question: In what way was he "Boss of Jersey City"?
Self-contained rewrite: In what way was Frank Hague the "Boss of Jersey City"?