According to custom, Middle Tennessee consists of that portion of the state east of the Tennessee River's western crossing of the state (in which it flows northward back into Tennessee after having flowed through northern Alabama) and west of the dividing line between the Eastern and Central time zones. Exceptions to this rule are that Hardin County, which is located on both sides of the Tennessee River, is considered to be entirely in West Tennessee and that Bledsoe, Cumberland, and Marion counties are generally considered to be in East Tennessee despite being in the Central Time Zone.
Middle Tennessee is characterized by rolling hills and fertile stream valleys. Its principal city, Nashville, is the state capital. Other major sizeable cities in Middle Tennessee include Clarksville and Murfreesboro. Geographically it is composed predominantly of the Nashville Basin and the Highland Rim, although the western portion of the Cumberland Plateau also extends into Middle Tennessee.
Middle Tennessee also has an abundance of institutions of higher learning—most notably Vanderbilt, Belmont, Lipscomb, and Tennessee State universities in Nashville and Tennessee Tech University in Cookeville. Other prominent universities are Austin Peay State University in Clarksville, the University of the South in Sewanee, Cumberland University in Lebanon, and Middle Tennessee State University in Murfreesboro, which is the state's second largest institution of higher learning, just behind the University of Tennessee in Knoxville.
Unlike the geographic designations of regions of most U.S. states, the term Middle Tennessee has legal as well as socioeconomic meaning. Middle Tennessee, West Tennessee, and East Tennessee are the state's three Grand Divisions. According to the Tennessee State Constitution, no more than two of the state supreme court's five justices can come from any one Grand Division. The Supreme Court rotates meeting in courthouses in each of the three divisions. The Supreme Court building for Middle Tennessee is in Nashville. A similar rule applies to certain other commissions and boards, in order to prevent a geographic bias. 
Middle Tennessee is the largest in area and least densely populated of the three Grand Divisions. At the 2000 census it had 2,069,976 inhabitants living in its 41 counties, which have a combined land area of 17,009.41 square miles (44,054.17 km²). Its population was 36.38 percent of the state's total, and its land area is 41.27 percent of the state's land area. Its population density was 121.696 inhabitants per square mile (46.987/km²) at the census.
- Tennessee Code Annotated 4-1-203, Middle grand division. Available from . "The middle division comprises the counties of Bedford, Cannon, Cheatham, Clay, Coffee, Cumberland, Davidson, DeKalb, Dickson, Fentress, Franklin, Giles, Grundy, Hickman, Houston, Humphreys, Jackson, Lawrence, Lewis, Lincoln, Macon, Marshall, Maury, Montgomery, Moore, Overton, Perry, Pickett, Putnam, Robertson, Rutherford, Sequatchie, Smith, Stewart, Sumner, Trousdale, Van Buren, Warren, Wayne, White, Williamson, and Wilson."
- Middle School Geography, Tennessee History for Kids, accessed August 3, 2010
- Tennessee Department of State, A History of Tennessee, Tennessee Blue Book, 2005-2006.
- Tennessee State Constitution