Mo. Rev. Stat. § 191.435
The department of health and senior services shall designate counties, communities, or sections of areas in the state as areas of defined need for health care, mental health, and public health services. If a county, community, or section of an area has been designated or determined as a professional shortage area, a shortage area, or a health care, mental health, or public health professional shortage area by the federal Department of Health and Human Services or its successor agency, the department of health and senior services shall designate it as an area of defined need under this section. If the director of the department of health and senior services determines that a county, community, or section of an area has an extraordinary need for health care professional services without a corresponding supply of such professionals, the department of health and senior services may designate it as an area of defined need under this section.
§ 191.435, RSMo