Most states saw voter turnout drop last year, driven in large part by young adults and non-Hispanic whites heading to the polls at lower rates than in years past.

In all, new estimates published by the Census Bureau indicate 38 states recorded declines in turnout of eligible voters compared to the 2008 general election, led by South Dakota (-6.8 percent), Alaska (-6.6 percent) and Oklahoma (-6.3 percent). The national turnout rate dipped to 61.8 percent last year, down from 63.6 in 2008 and 63.8 percent in 2004.

West Virginia was the only state with an estimated turnout below 50 percent -- only 47.8 percent of eligible voters casted ballots. Hawaii, president Obama’s childhood home, registered the next-lowest rate of 51.6 percent.

A few states did, though, experience a noticeable uptick in turnout.

Mississippi recorded the largest increase as eligible voter turnout swelled from 69.7 percent in 2008 to 74.5 percent last year – also the nation’s highest rate behind the District of Columbia. The state saw a similar jump in the percentage of eligible voters who were registered, up 7.2 percent from 2008.

So how did Mississippi have such a significant increase while turnout plummeted elsewhere? The answer is indicative of a national trend that saw eligible black voters turn out in record numbers.

The Census Bureau estimates 82.4 percent of eligible blacks voted in Mississippi, up nearly 10 percent from 2008. Here’s a table breaking down voter turnout in the state, comparing 2008 and 2012 estimates:

    2012 % Voter Turnout      2008 % Voter Turnout  
Total 74.5 69.7
White non-Hispanic   71.8 68.4
Black 82.4 72.9

Nationwide, the Census Bureau estimates 66.2 percent of eligible black voters casted ballots, a historic high that increased 1.5 percent from 2008. It marked the first time that blacks voted at a higher rate than whites since the Census began tracking eligible voters in 1996.

By contrast, national turnout among other race and ethnic groups fell slightly from 2008. Non-Hispanic white turnout decreased 2 percentage points; Hispanic turnout decreased 1.9 percent and turnout for Asian voters, who participated at the lowest rate of any group, dipped 0.3 percent.

Voting patterns among racial groups were not uniform across all regions, though.

Black voter turnout surpassed non-Hispanic white voters in much of the eastern part of the country, particularly in Mississippi, Alabama, Tennessee, Kentucky, Pennsylvania and New York. In the central region -- stretching from North Dakota down to Texas -- turnout was roughly the same. Out west, turnout among non-Hispanic whites continued to exceed that of black voters.

After Mississippi, the highest voter turnout gains found in states are likely attributable to Mitt Romney’s candidacy.

Utah, with its high Mormon population, saw turnout increase from 53.1 percent to 57 percent of eligible voters. Similarly, Massachusetts voters came to the polls in greater numbers with their former governor on the ballot as turnout increased 3.7 percent.

Other states registering smaller increases in estimated voter turnout from 2008 (although some were not considered statistically significant) were Idaho, Wisconsin, Colorado, North Carolina, Montana and Tennessee.

A drop-off in participation among younger voters also accounted for the lower turnout rates most states experienced.

White, Hispanic and black voters between the ages of 18 and 24 all came to the polls at lower rates than 2008. The only age group recording an increase was those 65 and older, who remain far more likely to vote than any other age group.

2012 Voter Turnout Map

 Please zoom out to view Alaska and Hawaii.

Change in Voter Turnout: 2012 and 2008

The following table shows estimated eligible voter turnout for all states, comparing 2008 and 2012 totals. Please note that some states have higher margins of error than others: