All-mail voting in Colorado increases turnout and reduces turnout inequality.

The COVID-19 crisis has generated interest in all-mail voting (AMV) as a potential policy solution for avoiding in-person elections. However, the quality of AMV implementation has varied greatly across states, leading to mixed results in previous research. We exploit the understudied 2014 implementation of AMV in Colorado to estimate the effect on turnout for all registered voters, along with age, racial, education, income and wealth, and occupational subgroups.