Of registered voters, nearly 43 percent cast a ballot, which represents a spike for a primary election. It topped voter turnout from 2008, which was about 41 percent, and in 2012, it was just shy of 30 percent.

On the Democratic side in Franklin County, voters gave a majority of votes to Sanders, as was the case across the region. Though Hillary Clinton claimed the most votes statewide, Sanders won most counties in Illinois, and all in Southern Illinois with the exception of three: Massac, Alexander and Pulaski. Clinton carried population centers in and near Chicago, and the Metro East.

In Jackson County, Democratic Party Chairman Mike Barone attributed the big Sanders vote to the student population at SIU, as Sanders has been popular with young people. But that doesn't explain the rest of the counties.

Jackson said he was surprised at the widespread support for Sanders across the state. He said it may be a case of voters on both sides of the aisle feeling disgruntled with so-called establishment candidates, and wanting to make a statement that it’s time for a change. Sanders comments about strengthening the middle class, and his stance against free trade agreements, also may have factored into the equation, Jackson said.