Post village located near Mississippi River about one hundred miles northeast of Jefferson City. Situated on Hannibal and St. Joseph Railroad. Incorporated 23 Nov. 1855. County seat. Population in 1850 about 1,300. Daniel Avery, who was kidnapped by group of Illinoisans and Missourians and taken to Missouri to face charges of horse theft, detained in Marion Co. jail in Palmyra, Dec. 1843.