title: What is rural? A focus on urban influence codes.
abstract: Classification of U.S. counties into metropolitan and nonmetropolitan masks a high degree of variation in population size, density, and relationship between urban and rural areas. This article reviews the urban influence county coding system and illustrates how it applies to U.S. counties. The urban influence codes can be useful for analysis of rural health policy.
authors.affiliation: Cecil G. Sheps, Center for Health Services Research, University of North Carolina at Chapel Hill 27599, USA.
authors.forename: L D
authors.initials: LD
authors.lastname: Baer
authors.forename: K D
authors.initials: KD
authors.lastname: Johnson-Webb
authors.forename: W M
authors.initials: WM
authors.lastname: Gesler
mesh_terms: D000043:Abstracting and Indexing; D002391:Catchment Area, Health / Q000706:statistics & numerical data*; D002965:Classification; D006291:Health Policy; D006801:Humans; D011156:Population Density; D012424:Rural Population / Q000145:classification*; D014481:United States; D014505:Urban Population / Q000145:classification*