Platt, Thomas Collier, 1833–1910, American legislator and political boss, b. Owego, N.Y. He was president of the Tioga County National Bank and had acquired considerable commercial interests by the time he served in the U.S. House of Representatives as a Republican (1873–77). In 1881 he became a U.S. Senator, but, following his mentor, Roscoe Conkling, in a quarrel with President Garfield over patronage, resigned almost immediately, thereby winning the nickname "Me Too" Platt. With Conkling he sought vindication in a new election but withdrew his name in the deadlock that followed in the state legislature. Platt remained prominent in New York politics, gaining new power and consolidating his control of patronage. Again from 1897 to 1909 he was a U.S. Senator. One of the most powerful of Republican politicians, he was largely responsible for the election (1898) of Theodore Roosevelt as governor of New York. Although Roosevelt often consulted with Platt, Roosevelt was largely independent in political matters, and in 1900 Platt succeeded in shelving him (as he thought) into the vice presidency. Afterward Platt's power declined.
See his autobiography (1910, repr. 1974); H. F. Gosnell, Boss Platt and His New York Machine (1924, repr. 1971).