The main purpose of this article is to examine why the variation in public education reform occurs among school districts. In the USA, school choice movement (SCM) has facilitated public education reform. It has provided scholars and political leaders with a competitive spirit and diverse innovative tools to reform America’s monopolistic and command-controlled public education system. Since many innovative SCM tools have been introduced to the conventional public education system in the early 1990s, the current picture shows that there is the significant variation in the degree of public education reform at the local level. Using Colorado’s school districts as the units of analysis, this article examines explanatory factors that lead this variation. The analyzed results of multiple ordinary least square (OLS) regression analysis indicate that three independent variables—mimetic diffusion, interest groups, and student population—are statistically significant. Namely, these final findings demonstrate that a neighboring jurisdiction, interest groups, and student population size play an important role as factors in explaining this variation of local public education reform in the USA. Meanwhile, this study contributes to making the logic of diffusion phenomenon more concrete and creating two new terminologies—‘mimetic diffusion’ and ‘coercive diffusion’—by integrating the similar contents of both diffusion model and isomorphism.