Platt was born on July 30, 1805, in
Plattsburgh, New York, the son of Isaac C. Platt and Ann Tredwell. His paternal grandfather was Judge Charles Platt, who was the first Supervisor of Plattsburgh, the first Judge of Clinton Common Pleas Court, town and county clerk, and brother of
Zephaniah Platt. His maternal grandfather was
Thomas Tredwell. During the
War of 1812, Platt was sent to Vermont and studied in the primary department of
Middlebury College, which his uncle
Henry Davis was president of. He then attended the Plattsburgh Academy. A farmer, he was considered one of the leading agriculturists in the county. He was the first president of the First National Bank of Plattsburgh and the Clinton County Savings Bank. He was prominently involved in the movement to build the
New York and Canada Railroad. Platt was
Supervisor in 1842 and 1854. He lost the 1858 re-election to
Republican Lewis W. Pierce. In the
1876 United States House of Representatives election, he was the Democratic candidate in
New York's 18th congressional district. He lost the election to Republican incumbent
Andrew Williams. Platt was an Elder of the
Presbyterian Church. In 1829, he married Ann Elizabeth Miller. Their children were Ann Elizabeth (wife of B. F. Felt of
Galena, Illinois), Caroline D. (wife of James Palmer), John D. of Nebraska, and Mary L. His wife died in 1871, and in 1873 he married Julia Haynes. He was buried in Riverside Cemetery in Plattsburgh. == References ==