There is no single, dominant issue captivating the public ahead of the 2014 elections. As Aaron Blake puts it, this election is about nothing. Or it's about anything you want it to be, according to Dan Balz.

Democrats focus on women’s issues and the minimum wage. Republicans zero in on Obamacare, Benghazi and executive overreach. But the public hasn’t bought into any one of these issues in a wholesale way.

Gallup polling tells the story. They’ve done a remarkable job of asking people to name the most important problem facing the country, nearly every month for three quarters of a century.

The latest results from July offer a decidedly mixed picture. What had been the dominant issue for most of President Obama’s tenure -- the economy -- is receding as economic indicators improve.

But no single item has emerged to overtake the economy in the top spot. Immigration has rocketed into the mix, with the crisis of children from Central America at the U.S.-Mexico border. One in six name immigration as the top problem, up from just one in 20 in June.

Other items that are rated as highly as immigration include dissatisfaction with the way the government is working (16 percent), the economy (15 percent) the related concern of jobs (14 percent) and health care mentions (8 percent). Each of these items have declined since January and February. Gallup catalogues more than 40 other separate items mentioned by 6 percent or fewer as the top problem.

So is this just the way midterm elections usually play out -- an election with no national candidates, no driving issue, but rather a series of local and state concerns? Not according to Gallup.

In the fall of virtually every midterm election year there has been at least one issue that has grabbed national attention. In data going back to 1946, only three times -- in 1998, 1990 and 1986 -- has attention been as divided as it is now.

What’s interesting about these Gallup trends is how they can buck conventional wisdom and memories about what drove voters in those years.

The 2010 campaign was all about Obamacare, right? Wrong. The top issue that year was the economy.

The 2002 election was about terrorism? Not so much. Again, the economy was the top problem.

Bill Clinton’s impeachment drove the 1998 election? Not even close. As noted above, this was a hodgepodge year with five different items all tightly packed together -- ethics, government dissatisfaction, education, the economy and crime.

Hillarycare, or the backlash to it, was at the core of the 1994 election? In fact, it was crime.

The Gallup trend tells the story of America’s recent history quite nicely, from inflation in the ‘70s, to Vietnam in the ‘60s to Russia in the ‘50s.

So what does this mean for the election and which side will it favor? That’s not so clear with the current data. Gallup asks a followup question: which party do people think is better able to handle the top problem people just mentioned? In July, the public split exactly evenly -- 35 percent said Republicans were. Another 35 percent pointed to Democrats.

The election is still three months out, and a big event could move the public to focus on one of these issues. Then again, it might not.