Question: The Emerald Mound Site (22 AD 504), also known as the "Selsertown site", is a Plaquemine culture Mississippian period archaeological site located near Stanton, on the Natchez Trace Parkway,is a National Parkway in the southeastern United States that commemorates the historic Old Natchez Trace and preserves sections of the original trail, are in which state? 

Context paragraphs:
Natchez Trace Parkway Land Conveyance Act of 2013: The Natchez Trace Parkway Land Conveyance Act of 2013 ( ) is a bill that was introduced during the 113th United States Congress.  The bill would require the National Park Service (NPS) to convey about 67 acres of property in the Natchez Trace Parkway to the state of Mississippi.  The legislation also would adjust the boundaries of the parkway to include 10 additional acres.  The two pieces of land in question originally belonged to Mississippi and were donated to the National Park Service when the NPS was trying to determine where to end the Natchez Trace Parkway.  Since the NPS did not choose to use either of the pieces of land, the state would like the land back.

Anna Site: The Anna Site (22 AD 500) is a prehistoric Plaquemine culture archaeological site located in Adams County, Mississippi 10 mi north of Natchez.  It is the type site for the "Anna Phase (1200 to 1350 CE)" of the Natchez Bluffs Plaquemine culture chronology.  It was declared a National Historic Landmark on September 14, 1993.

Plaquemine culture: The Plaquemine culture was an archaeological culture in the lower Mississippi River Valley in western Mississippi and eastern Louisiana.  Good examples of this culture are the Medora Site (the type site for the culture and period) in West Baton Rouge Parish, Louisiana, and the Anna, Emerald Mound, Winterville and Holly Bluff sites located in Mississippi.  Plaquemine culture was contemporaneous with the Middle Mississippian culture in the Cahokia site in St. Louis, Missouri.  It is considered ancestral to the Natchez and Taensa peoples.

Natchez Trace Parkway: The Natchez Trace Parkway (also known as the Natchez Trace or simply the Trace) is a National Parkway in the southeastern United States that commemorates the historic Old Natchez Trace and preserves sections of the original trail.  Its central feature is a two-lane parkway road that extends 444 miles (715 km) from Natchez, Mississippi, to Nashville, Tennessee.  Access to the parkway is limited, with more than fifty access points in the states of Mississippi, Alabama, and Tennessee.  The southern end of the route is in Natchez at an intersection with Liberty Road, and the northern end is northeast of Fairview, Tennessee, in the suburban community of Pasquo, Tennessee, at an intersection with Tennessee 100.  In addition to Natchez and Nashville, the larger cities along the route include Jackson and Tupelo, Mississippi, and Florence, Alabama.

Mangum Mound Site: Mangum Mound Site (22 CB 584) is an archaeological site of the Plaquemine culture in Claiborne County, Mississippi.  It is located at milepost 45.7 on the Natchez Trace Parkway.  Two very rare Mississippian culture repoussé copper plates have been discovered during excavations of the site.  The site was used as a burial mound during the Foster Phase of the culture (1350 to 1500 CE) and is believed to have been abandoned before the 1540 expedition of Hernando de Soto.

Emerald Mound Site: The Emerald Mound Site (22 AD 504), also known as the "Selsertown site", is a Plaquemine culture Mississippian period archaeological site located on the Natchez Trace Parkway near Stanton, Mississippi, United States.  The site dates from the period between 1200 and 1730 CE.  It is the type site for the "Emerald Phase (1500 to 1680 CE)" of the Natchez Bluffs Plaquemine culture chronology and was still in use by the later historic Natchez people for their main ceremonial center.  The platform mound is the second-largest Pre-Columbian earthwork in the country, after Monk's Mound at Cahokia, Illinois.

Boyd Mounds Site: The Boyd Mounds Site (22MD512) is an archaeological site from the Late Woodland and Early Mississippian period located in Madison County, Mississippi near Ridgeland.  Many of the mounds were excavated by The National Park Service in 1964.  It is located at mile 106.9 on the old Natchez Trace, now the Natchez Trace Parkway.  It was added to the NRHP on July 14, 1989 as NRIS number 89000784.

Foster's Mound: Foster's Mound (22 AD 503) is a Plaquemine culture archaeological site located in Adams County, Mississippi northeast of Natchez off US 61.  It is the type site for the "Foster Phase (1350-1500 CE)" of the Natchez Bluffs Plaquemine culture chronology.  It was added to the NRHP on September 2, 1982 as NRIS number 82003091.

Bynum Mound and Village Site: The Bynum Mound and Village Site (22CS501) is a Middle Woodland period archaeological site located near Houston in Chickasaw County, Mississippi.  The complex of six burial mounds was in use during the Miller 1 and Miller 2 phases of the Miller culture and was built between 100 BCE and 100 CE.  It was listed on the National Register of Historic Places in 1989 as part of the Natchez Trace Parkway at milepost 232.4.

Natchez Trace Trail: The Natchez Trace Trail is a designated National Scenic Trail in the United States, whose route generally follows sections of the 444 mi Natchez Trace Parkway through the states of Tennessee, Alabama, and Mississippi.  The Natchez Trace Trail is not envisioned as a long, continuous footpath, as is the case with other national scenic trails (such as the Appalachian Trail); rather, only a limited number of trail segments along the route, currently over 60 mi of trail, have been developed for hiking and horseback riding.  Moreover, the Natchez Trace Trail, unlike many others that rely heavily on volunteers for trail construction and maintenance, is managed and maintained by the National Park Service.  Sections of the trail follow along the Natchez Trace Parkway road shoulder, and cross county and state roads.

Supporting paragraphs: Emerald Mound Site Natchez Trace Parkway
Answer: Mississippi