What distinguishes the U.S. from Europe in this regard is the broader historical trend. While U.S. voter-turnout rates go up and down depending on the candidates, the national mood, and so forth, the EU’s voter-turnout rate has only ever gone in one direction: down. In many individual countries—but not all of them—voter participation has dropped significantly since each nation’s first European Parliament election. The chart below shows the percentage-point change in voter turnout between every country’s first European Parliament election and its most recent one. A negative percentage-point change indicates that voter participation has fallen…

For those countries that have been most harmed by the European debt crisis, the democratic deficit fuels a vicious cycle: Voters are alienated by EU policy decisions, leading them to disengage from a political process associated with those decisions, thereby giving them less influence over those decisions.

Consider the relationship between voter turnout and trust in the European Central Bank. The ECB led the eurozone’s fiscal response to the debt crisis, and its decisions have major ramifications for the European Union’s economic policy as a whole. According to a study by the European think tank Bruegel, trust in the ECB’s policies tends to correlate with voter turnout for European Parliament elections. “[The] ability to deliver financial relief through the ECB or alleviate national fiscal distress,” the researchers found, “helps create a more benign attitude to Europe, leading to higher voter turnout.”