Turnout compared even more poorly against other previous races. The Des Moines Register reported that the last competitive Iowa Republican Senate primary, in 1980, featured more than 259,000 voters. (Iowa's population has grown by more than 130,000 since 1980, to boot.)
In Georgia, another crowded GOP primary for the Senate couldn't generate enthusiasm among voters, either. Roughly 600,000 people voted in the Republican race (which led to a runoff between business executive David Perdue and Rep. Jack Kingston). That's far fewer than the 680,000 who showed up in the state's 2010 GOP primary, a difference of 13 percent.
Throughout Georgia, voter turnout clocked in below 20 percent, despite a plethora of competitive House primaries on the Republican side, according to The Atlanta Journal-Constitution. Still, a greater share of people voted in Georgia's primary than in California's, where an abysmal 18.3 percent of all eligible voters showed up.
Low turnout isn't just plaguing Senate races.
In Pennsylvania, for example, the Democratic Party's gubernatorial primary featured a longtime House member with the backing of national liberal groups such as EMILY's List (Allyson Schwartz), a rising-star state treasurer (Rob McCord), and a businessman from the state's famed conservative "T" with close ties to former Gov. Ed Rendell's administration (Tom Wolf).
Given Republican Gov. Tom Corbett's poor poll numbers, Democrats had extra reason to be excited that their nominee would become the state's next governor. But when the May 20 primary arrived, many voters didn't seem to notice. Roughly 840,000 Pennsylvania Democrats voted, down 18 percent (190,000 people) from the 1 million who cast their ballots in the party's 2010 gubernatorial primary.
The drop was even steeper compared with the 2002 primary for governor, when 1.24 million registered Democrats chose their candidate — a total nearly 50 percent greater than this year's turnout.
All of these primaries, in Pennsylvania, Iowa, and Georgia, featured competitive, multicandidate contests with a lot on the line for the fall. Iowa and Georgia hosted competitive Senate races that could very well determine which party controls the U.S. Senate. Corbett, the GOP governor in Pennsylvania, is usually regarded as the most vulnerable gubernatorial incumbent in the country. And although Wolf and Ernst won their races with larger-than-expected margins, most analysts considered these contests highly competitive not long ago.
In other words, each had all the ingredients of an interesting race.
So why the drop-off? Voters' deep dissatisfaction with Washington and politics in general might be keeping them away from the process altogether, convinced that their vote won't change a broken system. Or it might be that the gradual ideological homogenization of each party has left voters with fewer real differences among the candidates — and consequently, less interest in whoever emerges as the nominee. In 2002 in Pennsylvania, for instance, Casey was ostensibly an antiabortion candidate, while Rendell unequivocally backed abortion rights. By 2014, there were no such differences within the field.