Boss Tweed was an infamous figure in New York politics who dominated New York City in the mid-1800s, and essentially controlled the Democratic Party in New York state during his years in power. He is often pointed to as an iconic figure of corruption and ruthlessness, and his successful prosecution and imprisonment marked a critical turning point in New York politics. By undermining Tweed and Tammany Hall, the political machine he spearheaded, much of the rampant corruption in New York was put an end, setting the stage for a more egalitarian city.
Tammany Hall actually predates William Magear Tweed; it was created in the late 1700s as a general social club. By the time Tweed was born, in 1823, it had acquired a distinctly political bent, and as he grew into adulthood, he joined the club and began to rise in the ranks through hard work and well-placed bribes. In the 1850s, William Tweed served in the United States Congress, returning to New York to serve as a senator and to coalesce his growing political power.
By the 1860s, William Tweed had become Boss Tweed, and he was fully in control of Tammany Hall. He surrounded himself with cronies and assistants, and set about defrauding the city of New York, ultimately taking an estimated $100 million US Dollars (USD) from city coffers. Tweed accomplished this through the “Tweed Ring,” which ensured that all city contracts were awarded to his co-conspirators, and they in turn padded their bills, sending the extra money Tweed's way.
In addition to being a mastermind at corruption, Tweed was also very skilled at political manipulation. Through Tammany Hall, he invested in a number of public works projects that were designed to win the hearts of the lower classes, later using their loyalty to throw elections and ensure that Tammany Hall kept a stranglehold on New York politics. The political machine gave members of the working class a hand, and expected absolute loyalty in return.
In 1870s, news about Tammany Hall's corruption began to break, and by 1873, Boss Tweed was imprisoned for his role in the corruption scandal, as were many others. Contemporaries suggested that many people involved in the Tweed Ring got off lightly, because imprisoning everyone involved would have emptied the streets of New York City. Tweed briefly escaped prison, fleeing to Cuba and later Spain, but he was recaptured and sent back to the United States, where he died in 1878.
Tammany Hall limped along for a few decades after the downfall of Boss Tweed, playing a role in New York politics as late as the 1930s.