Arizona PCAs reflect similarities in demographics and primary care services utilization patterns. They are a common geographic unit adopted by the Arizona Department for Health Services for health statistical analysis. A specific methodology process, rules and exceptions were developed to guide the creation of PCAs, which are built from 2010 US Census Tracts. All PCAs have a population greater than 10,000 but less than 200,000, have an area no greater than 7500 square miles, shall not cross county lines, and shall follow existing political boundaries whenever possible. If no political boundary exists, demographics (in urban areas) and proximity to safety net facilities and neighboring communities (in rural areas) are used to form a PCA. There are a couple exceptions to these rules. Tribal PCAs are exempt from population and area minimum and maximum rules, and can cross county lines. If the Census Designated Place (CDP) that defines a PCA crosses county lines and its population adds up to at least 10,000 but less than 150,000 then the resulting PCA can cross a county line.