Young Voters in America

How does turnout rate amongst young voters impact elections?

From the US Census Bureau Current Population Survey (CPS)

48.52% turnout rate for 18-24 year olds

46.74% turnout rate for 18-24 year olds

36.10% turnout rate for 18-24 year olds

If the turnout rate was higher in 2000 and 2004 for the 18-24 year old age group, could the results of either election change? Do any specific demographics within this population have a signifcant impact?