Trying to predict voter turnout may be a bit like forecasting the weather. You take seasonal variations and local variables into consideration -- prevailing winds, storms, pressure, humidity -- and then you make an educated guess that it's going to rain. And then it doesn't rain. Or, in this case, voter turnout is higher or lower than expected.
But either way, historical trends can still give you a fair idea of what to expect.
Take a look at the following data from the California Secretary of State's office, and you can see, for instance, that the rate generally dips during midterm elections -- 1994, '98, '02, '06.
Hover your mouse over the charts to reveal the turnout rate for each year.
The blue area in the chart represents the total percentage of registered voters who cast a ballot. The red area is consistently smaller because we are comparing votes cast to the total number of eligible voters. The latter group consists of all citizens who are more than 18 years old (and aren't, say, convicted felons), and who have not registered to vote. There will always be more eligible voters than registered ones.
In a presidential election year, the numbers spike -- 1988, '92, '96, '00, and so on.
However, take a closer look and you'll see that even among presidential election years, there are trends. Compare the rate for '92, '96, and '00, and you'll notice a relative dip in the middle. That was a year in which we had an incumbent (President Bill Clinton was up for reelection). You can see the same trend again during the Bush years -- '00, '04, '08.
If we as voters adhere to this seesaw trend, then we're likely to see an uptick over the 2010 midterm election, but a downtick compared to 2008.
The dismal part of these numbers is fairly evident at first glance. The state enjoyed a clear and consistent increase in voter participation throughout the Civil Rights and Vietnam War years. But those democratic days were followed by a steep, decade-long slide beginning in 1976.
Since then, the turnout at primary elections has been rather lackluster. The only real exception came in 2008, when the fever and excitement leading up to the election of the nation's first black president drew people back out to the polls. Even then, the rate of registered voters who actually cast a ballot was only 57 percent, barely surpassing the lowest turnout of the '60s and '70s.
When you compare all this to the turnout at general elections, the picture becomes pretty clear: fewer voters want to be bothered with a primary, which seems far less important than the game night excitement of the general.
Again, past trends don't dictate the future. Voters turned out in greater numbers for the 1998 midterms than they had for the '96 presidential primary, for instance.
And voters have many reasons to voice their opinion on June 5. There will be a laundry list of items to decide, not to mention a new primary election system that could empower independent voters and significantly shape the outcome of key races well ahead of the general. But based purely on historical numbers, it doesn't look great.
Fingers crossed for California.