... is often described as the first US Minster to Mexico, but he wasn't the USA's first representative in that country. Wikipedia lists three individuals, two of them as Special Diplomatic Agents and one as Envoy, who served in sequence from 1812 to 1825 under President James Madison. Poinsett was appointed in 1825 by John Quincy Adams, and he is the first one whose title is given (by Wikipedia) as Minister.
US representatives in Mexico served under a variety of titles until 1898, when the first Ambassador was appointed. As well as Minister (the most common, and used exclusively from 1866 to 1898), several were styled as Special Diplomatic Agents and two as Chargés d'Affaires.
Poinsett, who served as Minister to Mexico from 1825 to 1829, was an accomplished amateur botanist. He was instrumental in founding the National Institute for the Promotion of Science and the Useful Arts, a precursor of the Smithsonian Institution.
© Haydn Thompson 2021