The issue of proximity for adult students has become increasingly salient as age demographics shift in higher education and states propose initiatives to increase adult degree completers. One way of alleviating proximity barriers for adults at universities has been to increase online courses and degrees. Nationally, online education experienced double-digit expansion between 1999 and 2010, followed by moderate but consistent growth in the years that followed. Using county-level data from 1999 to 2018 in Arkansas, we examined how a community's proximity to public universities is associated with its adult participation in public universities. To understand how this relationship may have changed with the proliferation of online education, we created growth models that control for time-varying community factors during this time (e.g., unemployment, population density, community college participation, and poverty). Our findings illustrate that participation grew sharply from 1999 to 2010 before stabilizing between 2011 and 2018, mirroring national online education trends. As proximity decreased, so did a county's adult participation, but this effect was not mitigated by the growth of online education. Interestingly, unemployment and poverty did not account for variation in a county's adult student participation. Implications for higher education policy and future research on adult participation are discussed.