Pintard's report was instrumental in convincing Thomas Jefferson to purchase the Louisiana Territory. He served as first city inspector of New York City for many years after 1804, and was authorized by the corporation of New York to issue fractional notes during the War of 1812. John was secretary of the Mutual Assurance Company from 1809 to 1829. From 1819 to 1829 he served as secretary of the New York Chamber of Commerce. He served as treasurer of the Sailor's Snug Harbor from 1819 to 1823 and was instrumental in the purchase of the property on Staten Island where the home is now located. He also was a founder of the New York Historical Society and the Massachusetts Historical Society. John Pintard served as manager of the state lotteries and was first sagamore of the Tammany Society. He was also elected a member of the American Antiquarian Society in 1814. In 1832 he was in New York City during the second cholera pandemic. On February 19, 1805 he began the efforts which became the present free school system in New York. He was also active in the movement that resulted in the building and completion of the Erie Canal. John Pintard surveyed the plans for the streets and avenues in upper New York City. A deeply religious man, he was one of the chief supporters of the General Theological Seminary and helped found the American Bible Society, which he always called his "brat." He was vestryman for the Huguenot Church of New York City for thirty-four years and his translation of the "Book of Common Prayer" from English to French is still used today. In 1822, the degree of LL.D. was conferred on him by Allegheny College. Pintard was an active Freemason, serving as Master for his Lodge in New York. Perhaps his greatest contribution to American society, however, was his role in establishing the modern popular conception of Santa Claus based upon the Dutch legend of Sinterklaas. His papers demonstrate that he personally observed the feast of St. Nicholas in an era when such remembrances were still frequently considered "hagiolatry" in America and when almanacs of the day omitted reference to such a feast day. His publication in 1810 of a pamphlet proposing St. Nicholas as the patron saint of New York City, and Patron Saint of his newly established New York Historical Society became a theme just following his friend Washington Irving publishing The History of Old New York in 1809, (itself coming from Irving's January 25, 1808 article in Salmagundi magazine).