Final answer:
Boss William Tweed, also known as 'Boss Tweed', rose to become one of New York City's most powerful party bosses through corrupt methods, such as graft bribery and rigging elections. He amassed a large fortune through kickbacks and bribes.
Step-by-step explanation:
Boss William Tweed rose to become one of New York City's most powerful party bosses in the 19th century. Tweed, also known as 'Boss Tweed', was a Democratic Party operative who used corrupt methods, such as graft bribery and rigging elections, to exert power and influence within New York City politics. He amassed a large fortune through kickbacks and bribes, ultimately becoming a significant figure in American political history.