What is policy diffusion in simple terms?

When one region or country adopts a new policy, neighbors and others see it and adopt similar policies, so the policy spreads.

Why do governments copy other governments' policies?

They learn from successes, compete for firms and residents, simply imitate, or face pressure from higher-level governments.

Policy Diffusion

🏛️ Politics & Public Administration By CampusDown Wiki Editorial Team Last updated October 27, 2026 Views 5

Policy diffusion is the process by which one government's adoption of a policy affects the likelihood that other governments adopt the same policy, so that policies spread across regions or countries. Jack Walker systematized it in 1969 through a study of policy innovation in the American states. It stresses that governments decide interdependently rather than in isolation.

Contents

1. Origins: state policy innovation
2. Methodological advances
3. Mechanisms of diffusion
4. FAQ
5. References

Origins: state policy innovation

Walker (1969) analyzed when American states adopted many policies and found that some states consistently innovated first while others followed, with neighboring states adopting around the same time. Gray (1973) tested whether cumulative adoption follows the S-shaped curve known from diffusion of innovations research and showed that patterns vary by policy area.

Methodological advances

Berry and Berry (1990) studied state lottery adoptions with event history analysis, estimating internal factors such as fiscal health and the external factor of neighbors' adoption in one model. The method became standard in diffusion research. Simmons and Elkins (2004) extended diffusion analysis to the cross-national level, showing that capital account and trade liberalization spread through competition and learning.

Mechanisms of diffusion

Shipan and Volden (2008) identified four mechanisms: learning from others' success, competition for firms or residents, imitation regardless of results, and coercion by higher-level governments. Graham, Shipan and Volden (2013) traced how diffusion research spread across subfields of political science and stressed the importance of distinguishing mechanisms.

FAQ

What is policy diffusion in simple terms?: When one region or country adopts a new policy, neighbors and others see it and adopt similar policies, so the policy spreads.
Why do governments copy other governments' policies?: They learn from successes, compete for firms and residents, simply imitate, or face pressure from higher-level governments.

Sources reviewed: 2026-10-26

References

Walker, J. L. (1969). The diffusion of innovations among the American states. American Political Science Review, 63(3), 880–899. The founding study of state policy diffusion.
Gray, V. (1973). Innovation in the states: A diffusion study. American Political Science Review, 67(4), 1174–1185. S-shaped adoption curves.
Berry, F. S., & Berry, W. D. (1990). State lottery adoptions as policy innovations: An event history analysis. American Political Science Review, 84(2), 395–415. Event history analysis of diffusion.
Simmons, B. A., & Elkins, Z. (2004). The globalization of liberalization: Policy diffusion in the international political economy. American Political Science Review, 98(1), 171–189. International diffusion of liberalization.
Shipan, C. R., & Volden, C. (2008). The mechanisms of policy diffusion. American Journal of Political Science, 52(4), 840–857. Four mechanisms of diffusion.
Graham, E. R., Shipan, C. R., & Volden, C. (2013). The diffusion of policy diffusion research in political science. British Journal of Political Science, 43(3), 673–701. Review of the field.
Rogers, E. M. (2003). Diffusion of innovations (5th ed.). Free Press. General diffusion theory.

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This article was last updated on October 27, 2026. It is based on widely recognized original works and textbooks; when citing it in a paper, please check the original sources listed in the references.