There is a consensus in recent literature on electoral research that voter turnout rates are declining significantly. We know less, however, about when this decline started and how significant it is. In this paper, we analyse trends in electoral turnout, as reported in the IDEA dataset for 20 stable democracies over the period between 1950 and 2012, which covers 349 elections. The results show that turnout levels were stable until approximately 1980. A significant linear decline can be observed from 1980 onward. Various institutional elements related to turnout levels – such as the closeness of elections, or the effective number of parties – do not explain this spline or the particular curve of the decline. We close with a number of suggestions for future research that may ascertain this relation in more depth.