The Oregon Office of Rural Health defines "Primary Care Service Areas" using the following criteria:
- Health resources are generally located within 30 to 40 minutes travel time.
- Defined areas are not smaller than a single zip code and zip codes used are geographically contiguous.
- Defined areas contain a population of generally more than 1,000 people.
- Areas constitute a "rational" medical trade or market area considering topography, social and political boundaries, and travel patterns. Additional considerations for service areas are boundaries that:
- Are congruent with any existing special taxing districts (e.g., health or hospital districts); and
- Include a population which has a local perception that it constitutes a "community of need" for primary health care services, or demonstrates demographic, socioeconomic or ethnic homogeneity. The population should be large enough (800 to 1,000) to be financially capable of supporting at least a single midlevel medical provider.