Mississippi is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Mississippi's western boundary is largely defined by the Mississippi River. Mississippi is the 32nd largest and 34th-most populous of the 50 U.S. states. Jackson is both the state's capital and largest city. Greater Jackson is the state's most populous metropolitan area, with an estimated population of 580,166 in 2018.