Palmyra is a city in and the county seat of Marion County, Missouri, United States. The population was 3,595 at the 2010 census. It is part of the Hannibal Micropolitan Statistical Area. Palmyra was platted in 1819, and named after Palmyra, in Syria. The settlement was designated county seat in 1827. A post office called Palmyra has been in operation since 1830.In 1862, the city was the scene of the Palmyra Massacre, in which ten Confederate prisoners were killed in retaliation for the disappearance of a local Union man.The Culbertson-Head Farmstead, Dryden-Louthan House, Gardner House, Marion County Jail and Jailor’s House, Peter J. Sowers House, Speigle House, Walker-Woodward-Schaffer House, and Ephraim J. Wilson Farm Complex are listed on the National Register of Historic Places.
Palmyra is located at 39°47′51″N 91°31′29″W (39.797396, -91.524857). According to the United States Census Bureau, the city has a total area of 2.76 square miles (7.15 km2), all land.As of the census of 2010, there were 3,595 people, 1,425 households, and 963 families living in the city. The population density was 1,302.5 inhabitants per square mile (502.9/km2). There were 1,557 housing units at an average density of 564.1 per square mile (217.8/km2). The racial makeup of the city was 95.1% White, 2.6% African American, 0.1% Native American, 0.3% Asian, 0.1% Pacific Islander, 0.4% from other races, and 1.4% from two or more races.
information provided by wikipedia.org