Expansive and restrictive state electoral institutions have been instrumental in structuring the vote throughout American history. Studies focused on a small number of reforms, years, or states lack the scope necessary to comprehensively evaluate the effects of institutional change over time. This work, however, places recent reforms in historical context and offers a long-term perspective. Using an original data set, it identifies the institutions that have generated the most substantial effects on state turnout rates during presidential elections from 1920 to 2000. Findings demonstrate that restrictive laws (those aiming to limit the vote or make voting more costly) produced large and consistently negative effects in the Southern and non-Southern states alike, but the effects associated with expansive reforms (those making participation more convenient or less costly) vary. Although a few expansive laws have increased turnout in the non-Southern states, they have had no effect in the Southern states where turnout rates are lowest.