is a county located in the southern portion of the U.S. state of Missouri. As of the 2010 census, the population was 10,881. Its county seat is Alton. The county was officially organized on February 14, 1845, and was named for the Oregon Territory in the northwestern United States.
Home to a large area of the Mark Twain National Forest, Oregon County contains more national forest acreage than any county in the state of Missouri. It also contains the Irish Wilderness, the largest federally protected wilderness area in the state. Hiking, backpacking, and horseback riding opportunities abound on the Ozark Trail and the White's Creek Trail. Canoeing, kayaking, jonboating, and fishing are popular on the Eleven Point River, which is Missouri's only National Wild and Scenic River.
Eleven Point State Park is a Missouri state park under development east of Alton, Missouri that includes 6 miles of Eleven Point River frontage.
Grand Gulf State Park is a Missouri state park just west of Thayer that includes a collapsed karst canyon.
Oregon County was created in 1845, at a time when the Oregon boundary dispute was a major issue.
During the American Civil War, men from Oregon County enlisted to fight for the Confederate States of America on three separate occasions.
In July 1861, the Second Infantry Regiment of McBride's Seventh Division, Missouri State Guard was formed. Oregon County men made up Companies A, D, F, and G. On August 10, 1861 they fought at the Battle of Wilsons Creek near Springfield and were victorious.
In early 1862 the Missouri State Guard was disbanded and regular Confederate Army units were formed. During February and March 1862, Oregon County men were mustered into companies D and I of the Fourth Missouri Infantry Regiment. The Fourth Missouri was sent to Mississippi, where they took part in the Battle of Corinth on October 3-4, 1862. The Oregon County men suffered heavy losses to both disease and battle casualties, and surrendered with 30,000 other Confederates after the Siege of Vicksburg ended on July 4, 1863.
In the late winter and spring of 1864, Major Matthew G. Norman began organizing a regiment of cavalry. They would join with men from northern Arkansas men led by Lt. Colonel James H. Tracy to form Fristoe's Regiment, Missouri Cavalry. Colonel Edward T. Fristoe, a native of Rappahannock, Virginia, would lead his regiment during General Sterling Price's ill-fated Missouri raid in the fall of 1864.
Other units Oregon County men enlisted in were Freeman's Regiment, Missouri Cavalry, and the Fifteenth Missouri Cavalry Regiment from neighboring Ripley County. Only a few Oregon County men joined the Union Army. Oregon County suffered greatly during the war from raids by Union troops, as well as from atrocities committed by bushwhackers supporting neither side.