Code	Description
Metro counties
1	Counties in metro areas of 1 million population or more
2	Counties in metro areas of 250 000–1 million population
3	Counties in metro areas of fewer than 25 000 population
Non-metro counties
4	Urban population of 20 000 or more, adjacent to a metro area
5	Urban population of 20 000 or more, not adjacent to a metro area
6	Urban population of 2500–19 999, adjacent to a metro area
7	Urban population of 2500–19 999, adjacent to a metro area
8	Completely rural or less than 2500 urban population, adjacent to a metro area
9	Completely rural or less than 2500 urban population, not adjacent to a metro area