Iowa Caucuses: What's at Stake Tonight

— -- The first voting of the 2016 presidential election cycle happens tonight. A useful tidbit to keep in mind: although candidates have been traipsing across the Hawkeye State for months, Iowa is not mathematically crucial for winning the nomination.

To win their party's respective nomination, candidates must win a certain number of delegates, or people who will ultimately vote for them at their party's convention in the summer. (Republicans need 1,237 delegates, while Democrats need 2,382.) Technically, a candidate could fare terribly in Iowa and still have a chance of getting the delegate numbers by the end of the race.

Iowa is important, however, because it shows the country how the candidates are faring in the race so far, and how the Iowa voters have responded to their messages. Historically it has helped propel candidates, including underdogs like Jimmy Carter and Barack Obama, to other victories. On the flip side, candidates often realize after the caucuses that there is no viable path for them to the nomination.

Caucuses are party-run events, so both the GOP and Democrats have different rules and delegate numbers, as you will see below. Here's what you need to know about what's at stake:

TIMING:

Doors at caucus locations close at 8 p.m. ET (GOP and Democratic)

The first results can be expected as early as 8:30 p.m. or 9 p.m. ET

BY THE NUMBERS:

Democrats:

An estimated 52 delegates are to be awarded tonight -- 8 of these are super delegates, people (usually party leaders) who do not have to commit to a candidate tonight. To receive any delegates, candidates must receive at least 15 percent of the vote. If a candidate receives 15 percent support, the delegates are awarded proportionally. Democratic caucus goers do not have to support any of the three candidates -- uncommitted is an option.

Republicans:

An estimated 30 delegates are to be awarded tonight. Delegates are awarded proportionally. However, unlike the Democrats, there is no minimum threshold that candidates need to be eligible for delegates. This means that it’s plausible each candidate could wind up with at least one delegate. Additionally, voting for "uncommitted" is not an option.

Historical Context

GOP

In 2012, Rick Santorum won with 25 percent of the vote, narrowly defeating Mitt Romney, who also had 25 percent. Ron Paul came in third place with 21 percent. The turnout at the caucuses 4 years ago was over 121,000 people.

In 2008, Mike Huckabee won with 35 percent of the vote, followed by Romney with 25 percent. John McCain, who ultimately won the nomination, and Fred Thompson tied for third with 13 percent. Approximately 120,000 people caucused that year.

Democrats

President Obama ran unopposed last cycle. But in 2008, he emerged victorious, winning 38 percent of the vote. John Edwards came in second with 30 percent, while Hillary Clinton, whom many had deemed the inevitable front-runner, came in third with 29 percent. According to the Iowa Democratic Party, turnout that year was 239, 872.

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