| The purpose of the RUCA 7-level code aggregation is to highlight the distinction between core areas and their peripheries, with the exception of the isolated areas, which are not defined by a core area. This classification method is useful for understanding the hierarchies within different levels of urbanity (i.e. large urban, large rural, small rural). The RUCA codes are classified as follows: |
| Urban core—metropolitan areas in which most of the commuting is within the urbanized area with a population of 50,000 or more or its peripheral areas |
| Other urban—metropolitan areas with primary commuting patterns to another urbanized area, and micropolitan, small towns, and rural areas in which the commuting is to another, larger urbanized area |
| Large rural core—micropolitan areas in which primary commuting patterns are within a large urban cluster with a population of 10,000–49,999 |
| Other large rural—micropolitan areas in which primary commuting patterns are to large urban clusters with populations of 10,000–49,999 |
| Small rural core—small towns in which primary commuting patterns are within a small urban cluster with a population of 2,500–9,999 and secondary commuting patterns are to larger urbanized areas or large urban clusters with populations of 10,000–49,999 |
| Other small rural—small towns in which primary commuting patterns are to small urban clusters with a population of 2,500–9,999 and secondary commuting patterns are to larger urbanized areas or large urban clusters with populations of 10,000–49,999; and |
| Isolated rural—rural areas in which the primary commuting patterns are to areas that lie outside an urbanized area or urban clusters and secondary commuting patterns are to larger urbanized areas, large urban clusters with populations of 10,000-49,999 or small urban clusters with a population of 2,500–9,999 |
