Public health systems vary by degree of centralization, reflecting the distribution of authority, responsibility, and effort between state and local public health agencies. We analyzed data from the 2008 National Association of City and County Health Officials Profile of Local Health Departments survey, and propose an improved composite measure of centralization that can be computed for all local health departments within a state, as opposed to a single state respondent, as done in 1998. While most states' structures (79.5%) are decentralized, the new measure presents a continuum from highly decentralized to highly centralized. The measure was internally consistent (Cronbach α = .87) and correlated somewhat strongly with the centralization classification from the 1998 survey (Kendall's τ correlation = .62, P < .001), suggesting that a stable centralization construct can be reliably determined. This new centralization variable can facilitate more nuanced studies of public health systems, and inform policy design and implementation.