How well does public policy represent mass preferences in U.S. states? Current approaches provide an incomplete account of statehouse democracy because they fail to compare preferences and policies on meaningful scales. Here, we overcome this problem by generating estimates of Americans' preferences on the minimum wage and compare them to observed policies both within and across states. Because we measure both preferences and policies on the same scale (U.S. dollars), we can quantify both the association of policy outcomes with preferences across states (responsiveness) and their deviation within states (bias). We demonstrate that while minimum wages respond to corresponding preferences across states, policy outcomes are more conservative than preferences in each state, with the average policy bias amounting to about two dollars. We also show that policy bias is substantially smaller in states with access to direct democratic institutions.