Chattanooga is a city in and the county seat of Hamilton County, Tennessee, along the Tennessee River bordering Georgia. With an estimated population of 180,557 in 2018, it is the fourth-largest city in Tennessee and one of the two principal cities of East Tennessee, along with Knoxville. Served by multiple railroads and Interstate highways, Chattanooga is a transit hub. Chattanooga lies 118 mi northwest of Atlanta, Georgia, 112 mi southwest of Knoxville, Tennessee, 134 mi southeast of Nashville, Tennessee, 102 mi east-northeast of Huntsville, Alabama, and 147 mi northeast of Birmingham, Alabama.