The long-term trend shows that 55 percent to 60 percent of eligible voters cast their ballots in a presidential election, while about 40 percent of eligible voters vote in mid-term elections, when many governors and other state officers, as well as the U.S. House and one-third of the U.S. Senate are elected.

These figures—relatively unchanged during the past two decades—are far below that of other Western nations, many of which boast voter turnout rates in excess of 80 percent.

Participation data reveal clear patterns about who is most likely to vote and who isn’t. If you are old, white, educated and strongly rooted in your community, you are more likely to vote. If you are young, non-white, less educated and move frequently, you are less likely to vote.

While these patterns generally hold true across states, there is great variation in voter turnout among the 50 states. For example, in the 2006 mid-term election, 55 percent of eligible Minnesotans went to the polls, while only 29 percent of North Carolinians voted.

Some of this variation can be explained by who lives in a state and who is ruled eligible under state law. For example, nationwide, around 10 percent of the voting age population is ineligible to vote. But, in California, 20 percent are ineligible; and, in Montana, one percent is ineligible. Most of this variation can be attributed to the size of a state's immigrant and prison populations.

Variation in voter turnout across states is also impacted by the voter registration rates. Self-reported registration rates vary dramatically, from a high of 89 percent in North Dakota, to a low of 53 percent in Hawaii. Some states offer registration up to and on Election Day, and these states tend to have higher overall registration rates.

Research shows that competitive elections increase voter turnout, but the amount of money required to run for office can deter or doom candidates who would otherwise engender broad public support. For example, in 2004, the average candidate needed around $110,000 to run for a seat in the upper chamber of a state legislature, and the average candidate needed more than $300,000 in California, Illinois and Texas.

As states increasingly take the lead on policy reform with respect to climate change, immigration and other issues, who votes and who doesn’t—and why—matters more and more.

Who is making decisions for your state?