Voter turnout is the percentage of eligible voters who cast a ballot in an election. Eligibility varies by country, and the voting-eligible population should not be confused with the total adult population. ... Low turnout is usually considered to be undesirable.
Voter turnout in the United States fluctuates in national elections. In recent elections, about 60% of the voting eligible population votes during presidential election years, and about 40% votes during midterm elections. Turnout is lower for odd year, primary and local elections.