From Borders to Networks: The Changing Channels of Education Policy Diffusion in the American States

Abstract How do spatial proximity, policy networks, and temporal dynamics interact to shape education policy diffusion across the American states and have these channels of influence changed over time? This study introduces an integrated framework combining spatial-X (SLX) estimation, exogenously constructed policy-pathway network exposure, and discrete-time survival models with policy-level random intercepts to decompose the relative contributions of geographic, relational, and temporal channels. Drawing on 10 education policies from the State Policy Innovation and Diffusion (SPID) database (1896–2017), with the policy-pathway network constructed from 714 non-education SPID policies to address within-domain endogeneity concerns, the analysis finds that geographic proximity and network exposure each predict adoption, although their relative importance has shifted across historical periods. For policies whose diffusion windows opened before 1970, geographic proximity is the dominant detectable channel; for policies opening after 1970, network exposure displaces geography. Spatial effects are detectable for K-12 policies but not for higher-education reforms, where statistical power is limited. A complementary spatial Durbin model on rapid-diffusion versus sequential-diffusion subsamples shows that contemporaneous (SAR) determination dominates for policies that diffuse in fewer than seven years, while temporally lagged (SLX) determination dominates for sequential-diffusion policies. A SPID-wide replication on 635 policies and 17,628 adoption events confirms both spatial signals across the broader policy landscape. These findings reveal how the institutional infrastructure connecting American states has evolved from geography-mediated to network-mediated channels, with implications for diffusion theory, methodological practice, and intergovernmental policy coordination.