T.C.A. § 6-58-104(a)(2) specifies that the comprehensive growth plan must identify the following three (3) types of areas if they exist within the county:

1. Urban Growth Boundary (UGB) - a reasonably compact area that contains the corporate limits of a municipality and the adjoining territory where high density commercial, industrial, or residential growth is expected.
2. Planned Growth Area (PGA) - compact sections outside incorporated municipalities and outside growth boundaries where high or moderate density growth is expected, if there are such areas in the county; new incorporations may occur only within these regions.  A county has authority to provide services within a PGA and to set a separate tax rate for these services.
3. Rural Area (RA) - territory that is not within another zone and that is to be preserved for uses other than high density development.

Several factors must be taken into account in determining the boundaries of these three (3) areas:

1. Population growth projections, to be developed in conjunction with the University of Tennessee;
2. Current and projected costs of infrastructure, urban services, and public facilities needed for development and methods to finance these needs;
3. The need for additional land area for high density development, after considering the feasibility of redeveloping all sites within the current boundaries;
4. The effect of development upon agricultural land, forests, recreational areas and wildlife management areas; and
5. The likelihood of eventual incorporation into a municipality.

T.C.A. § 6-58-106(a).