Portrait of Platt, by Samuel F. B. Morse, 1828
|Member of the New York State Senate|
July 1, 1809 – June 30, 1813
|Member of the U.S. House of Representatives|
from New York's 9th district
March 4, 1799 – March 3, 1801
|Preceded by||John Williams|
|Succeeded by||Benjamin Walker|
|Member of the New York State Assembly|
July 1, 1795 – June 30, 1796
|Born||June 30, 1769|
Poughkeepsie, Province of New York, British America
|Died||February 22, 1834 (aged 64)|
Peru, New York, United States
|Relations||Charles Z. Platt (brother)|
|Children||8, including Zephaniah|
Mary Van Wyck Platt
Platt was born on June 30, 1769 in Poughkeepsie, Province of New York, in what was then British America. He was the son of politician and lawyer Zephaniah Platt (1735–1807), who founded Plattsburgh, New York, and his second wife, Mary Van Wyck Platt (1742–1809). Among his siblings was New York State Treasurer Charles Z. Platt.
He practiced law in Poughkeepsie and served as the county clerk of Herkimer County, New York, from 1791 to 1798. He was also the county clerk of Oneida County, New York, from 1798 to 1802. He was a member of the New York State Assembly in 1796.
Platt was elected as a Federalist to the Sixth Congress, and served from March 4, 1799, to March 3, 1801. He was the chairman of the United States House Committee on Revisal and Unfinished Business. Afterward, he resumed the practice of law and served as a general in the Cavalry in the New York State Militia. In 1810, he was an unsuccessful candidate for governor. He was a member of the New York State Senate from 1809 to 1813. He was also a member of the Council of Appointment in 1813.
He married Helena Livingston (1767–1859), the daughter of Dr. Henry Livingston and Susannah Storm (née Conklin) Livingston. She was also the sister of Continental Congressman Gilbert Livingston, the Rev. Dr. John Henry Livingston, president of Queen's College, and author Henry Livingston Jr. (the grandfather of U.S. Senator Sidney Breese and Admiral Samuel Livingston Breese), among others. Together, Jonas and Helena were the parents of eight children, including:
- "PLATT, Jonas - Biographical Information". bioguide.congress.gov. Biographical Directory of the United States Congress. Retrieved 5 July 2018.
- Livingston, Edwin Brockholst (1910). The Livingstons of Livingston Manor: Being the History of that Branch of the Scottish House of Callendar which Settled in the English Province of New York During the Reign of Charles the Second; and Also Including an Account of Robert Livingston of Albany, "The Nephew," a Settler in the Same Province and His Principal Descendants. Knickerbocker Press. Retrieved July 5, 2018.
- United States Congress. "Jonas Platt (id: P000381)". Biographical Directory of the United States Congress.
- Livingston family tree
|U.S. House of Representatives|
| Member of the U.S. House of Representatives
from New York's 9th congressional district