During the 2004 Presidential Election, voter turnout was significantly higher in states where the margin of victory for either candidate was less than 10%.
The states that George Bush won by less than five percent of the vote were: Iowa, Colorado, Ohio, New Mexico and Nevada. The states that Bush won by between five percent and ten percent were: Missouri, Florida, Virgina and Arkansas.
Of those states, only New Mexico, Nevada and Arkansas saw voter participation of less than the national average of 60%.
The states that John Kerry won by less than five percent of the vote were: Minnesota, Wisconsin, New Hampshire, Oregon, Michigan and Pennsylvania. The states that Kerry won by between five percent and ten percent were: Maine, Washington, Delaware, New Jersey, California and Hawaii.
Of those states, only California and Hawaii saw voter participation of less than the national average. And California was essentially right at the national average.