Post was born near Westbury, New York on April 4, 1771.[1] He was the son of Jotham Post Sr. (1740–1817), with whom he was very close, and his wife, Winifred (née Wright) Post (1745–1811).[2] His older brother was Dr. Wright Post, a professor of surgery and anatomy at Columbia.[3]
He studied medicine, but did not practice, instead, he engaged in the drug-importing business in New York City. He served as member of the board of aldermen.[1] He served in the State assembly 1795 and 1805–1808.[4] He served as director of the New York Hospital from 1798 to 1802.[3]
Post was elected as a Federalist to the Thirteenth Congress, serving from March 4, 1813 to March 3, 1815.[1]
Julia Lynch Post (1797–1878), who married James DeWolf Jr., a son of politician James DeWolf, in 1815.[2]
Eleanor Post (1799–1872), who married Francis LeBaron DeWolf, also a son of politician James DeWolf, in 1820. After his death, she married John Whipple in 1839.[2]
Jotham William Post (1801–1841), who married Angelina Thayer Byers.[2]
Edwin Augustus Post (1804–1888), who married Lucretia Ann Main (1792‒1863). After her death, he married Cornelia Davis.[2]
Nancy Elizabeth Mary Post (1806–1895), who married Bernard Rhinelander (1800–1844).[2]
Magdalen Rachel Post (1810–1841), who married Isaac Gibson.[2]
After the death of his first wife in 1811, Jotham married Julia Strong on October 2, 1815 in Albany, New York. She was the widow of George Wattles.[2]
