Millen lies on the Ogeechee River in Jenkins County, approximately fifty miles south of Augusta, and is the county seat. The earliest settlement in the area, dating back to 1835, Millen was originally called "79" due to its approximate distance from Savannah. At the time, the settlement straddled the line between Burke and Screven counties.
The driving force behind the development of Millen was the railroad boom that swept Georgia in the 1840s and 1850s. In 1854 the Central of Georgia Railway, originating from Savannah, and the Georgia Railroad, originating from Augusta, connected at 79. Soon the town became known as Millen's Junction, named for McPherson B. Millen, the superintendent of the Central of Georgia Railway. Shortly thereafter a train depot, warehouses, and a hotel sprang up in Millen's Junction.
During the Civil War (1861-65) a site for a prison camp to house Union soldiers was chosen just outside of Millen's Junction. Fort Lawton was built in what is today Magnolia Springs State Park; the location was favorable because of its easy access to water, which was supplied by the springs, and because of its proximity to the railroad. On December 3, 1864, Sherman's March to the Sea passed through Millen. Prior to the arrival of Union forces, Confederate soldiers evacuated the Fort Lawton prisoners to Savannah. Union troops found the existence of the prison camp and the proximity of a train depot sufficient reason to destroy Millen's Junction.
After the war, the town was rebuilt. In 1881 the city, now called Millen, was incorporated by an act of the state legislature. As the town began to grow, residents in and around Millen began to lobby for the creation of their own county. The city was oddly positioned at almost the exact corner of four very large counties: Bulloch, Burke, Emanuel, and Screven. The county lines of Burke and Screven ran directly through the center of town, which made it difficult for Millen citizens to conduct business at the various county seats, especially by horse and wagon. In 1905 the state legislature created Jenkins County. Millen was named the county seat, and a courthouse was built there in 1910.
According to the 2010 U.S. census, the population of Millen was 3,120. Today Millen's economy is based primarily on agriculture, agribusiness, and forestry resources. The town has its own hospital, Jenkins County Hospital, and is the site for the county's elementary, middle, and high schools.
Residents celebrate a fall festival, known as the Fair on the Square, each October at the courthouse square. The festival consists of arts and crafts and games for children. Nearby Magnolia Springs State Park offers a freshwater aquarium and a variety of opportunities for recreation that include hiking, biking, swimming, and fishing.