Tennessee County Map: All 95 Counties

Under Article VI and Article XI of the 1870 Tennessee Constitution, the state is divided into Three Grand Divisions: East Tennessee (Appalachian mountains and Great Valley, centered on Knoxville and Chattanooga), Middle Tennessee (Nashville Basin and Highland Rim, centered on Nashville), and West Tennessee (alluvial plain between the Tennessee and Mississippi rivers, centered on Memphis).

State law mandates that the five justices of the Tennessee Supreme Court must be balanced across the Three Grand Divisions: no more than two justices may reside in any single Grand Division. Furthermore, the Supreme Court is constitutionally required to rotate sessions among courthouses in Knoxville, Nashville, and Jackson.

This legal tri-partism is symbolized by the three white stars on the Tennessee state flag, ensuring that county interests in rural mountain hollers, suburban bluegrass valleys, and Mississippi Delta cotton fields maintain balanced representation in state government.

By the late 1950s, rapid suburban growth outside the City of Nashville caused severe sewer, fire, and school crises in unincorporated Davidson County. In 1962, voters approved a unified charter, creating the Metropolitan Government of Nashville and Davidson County ("Metro").

Metro Nashville eliminated overlapping city and county taxes, established an Urban Services District and General Services District, and created a single Metropolitan Mayor and a 40-member Metropolitan Council.

Following this success, Moore County and the City of Lynchburg (home of the historic Jack Daniel's distillery) consolidated in 1988 into the Metropolitan Government of Lynchburg-Moore County. Trousdale County (Hartsville) followed with consolidation in 2001, streamlining services in Tennessee's smallest geographic county.