The frontrunners for mayor. Clockwise, from top left: Jenny Durkan, Bob Hasegawa, Mike McGinn, Cary Moon, Jessyn Farrell, Nikkita Oliver
The frontrunners for mayor. Clockwise, from top left: Jenny Durkan, Bob Hasegawa, Mike McGinn, Cary Moon, Jessyn Farrell, Nikkita Oliver nate gowdy, washington state legislature, LINDSEY WASSON, nate gowdy, kelly o, steven hsieh

The huge field of mayoral candidates—21 total—doesn't just foretell a summer of candidate forums featuring Nazi-saluting city council troll Alex Tsimerman. Many candidates also means that a few voters could decide who becomes mayor.

Just how few? Let's take a look at Seattle's last mayoral election.

Turnout in the 2013 primary was just 35 percent of registered voters. With nine candidates in the 2013 mayor's race, Ed Murray and Mike McGinn made it through the primary with less than 30 percent of the vote each. About 42,000 people voted for Murray and about 40,500 voted for McGinn. Another way of looking at it: The city's population that year was about 652,000. The people who voted for McGinn and Murray made up just 12.6 percent of residents.

And who were those voters?

Check out these maps. On the left: voter turnout across King County in 2013. On the right: median income and then the white share of neighborhoods across the city. Generally speaking, turnout is higher among wealthier, white people. More people vote in north Seattle than south Seattle. (Explore the maps for yourself here and here.)

Click to enlarge. Full maps here and here.
Click to enlarge. Full maps here and here. king county, sightline institute

Click to enlarge. Full maps here and here.
Click to enlarge. Full maps here and here. king county, sightline institute

There are twice as many mayoral candidates this year than 2013. And it's not just that there are more people running for mayor. There are more people with a shot at actually becoming mayor. In 2013, there were four real contenders, including the incumbent. This year, there are six serious candidates and no incumbent. Two candidates will make it through the August 1 primary to the November election and, if this year is like 2013, they'll make it through with the support of just a small fraction of Seattleites. That means your vote counts even more than in the typical mayoral race, where your vote already counts dramatically more than in presidential elections. (Don't even get me started on turnout for Seattle City Council elections. Voter turnout was just 30 percent in 2015, when all nine seats on the council were up for grabs at once.)

Want to make sure you have a say? Check your voter registration here.

Start a new registration here.To register online, you need a current Washington State driver license or ID card. If you don't have an ID, register by mail using this form or in person at the King County elections office in Renton or at the King County Administration building downtown.

If you don't currently have a residential address, you can use the address of a shelter, park, intersection, or "other identifiable location." You can receive your ballot at a shelter, friend's house, or by general delivery at the post office. If you want help keeping your address confidential, click here. If you're a non-citizen, know the risks associated with registering to vote.

To vote in the August primary, the deadline to register online or by mail is July 3. The deadline to register in person is July 24.