Punctuated Equilibrium Theory and the Diffusion of Innovations

This article builds on punctuated equilibrium theory to evaluate the diffusion of public policy innovations in the United States. The article argues that punctuated equilibrium theory provides a unifying framework for understating three mechanisms leading to the diffusion of innovations: gradual policy diffusion driven by incremental policy emulation, rapid state‐to‐state diffusion driven by policy imitation and mimicking, and nearly immediate policy diffusion driven by state‐level responses to a common exogenous shock. Drawing upon the Bass mixed influence diffusion model, this research generates measures of the coefficients of external and internal influences for diffusion for 81 public policy innovations that have spread across the United States. The article then evaluates how the policy image and direct participation of the federal government contribute to distinct patterns of diffusion over time.