Thomas Collier Platt, a Representative and a Senator from New York was born in Owego, New York. He was prepared for college at the Owego Academy and attended Yale College in 1849 and 1850. In 1852 he engaged in business as a druggist and continued for twenty years. He was president of the Tioga National Bank and was interested in the lumbering business in Michigan. He also acted as president of the Southern Central and other railways.

He was clerk of Tioga County 1859-1861. He was elected as a Republican to the Forty-third United States Congress and the Forty-fourth United States Congress (March 4, 1873-March 3, 1877).

He was elected as a Republican to the United States Senate in 1881, and served from March 4, 1881, to May 16, 1881, when Roscoe Conkling and he resigned because of a disagreement with President James Garfield over federal appointments in New York. He was an unsuccessful candidate for election to the United States Senate to succeed himself. He was the chairman, Committee on Enrolled Bills (Forty-seventh Congress). He was secretary and director of the United States Express Co. in 1879 and elected president of the company in 1880. He was a member and president of the Board of Quarantine Commissioners of New York 1880-1888. He was a member of the Republican National Committee and was elected to the United States Senate in 1896 and was reelected in 1903. He served from March 4, 1897, to March 3, 1909 and was not a candidate for reelection. He served as chairman of the Committee on Transportation Routes to the Seaboard (Fifty-fifth Congress). He was on the Committee on Printing (Fifty-sixth through Sixtieth Congresses), the Committee on Cuban Relations (Fifty-ninth Congress), the Committee on Interoceanic Canals (Fifty-ninth Congress).

He died in New York City, March 6, 1910 and was interred in Evergeen Cemetery, Owego, N.Y.