UPDATE: 11:50 p.m. EST — Iowa is feeling "The Bern." Vermont Sen. Bernie Sanders recounted his unlikely rise to victory Monday night as an adoring crowd chanted "Feel the Bern." Nine months ago, he had no money and no hopes of winning a contest against Hillary Clinton, he said.
"It looks like we are in a virtual tie," Sanders said with a laugh as the crowd yelled, "Bernie! Bernie! Bernie! "While the results are still not complete, it looks like we will have half of the Iowa delegates."
Live Iowa Results Map
Candidate photos courtesy of Getty. Photos by Alex Wong, Andrew Burton, Darren McCollester, Ethan Miller, Frederic Brown, Justin Sullivan, Mandel Ngan/AFP, Saul Loeb, Scott Olson and Win McNamee. A "County Margin of Victory" refers to the percentage points between the first place and second place winners in that county.
UPDATE: 11:30 p.m. EST — Hillary Clinton praised her "young" volunteers Monday night after tying with Bernie Sanders in the Iowa Democratic caucuses. "I am a progressive who gets things done for people," she said, signaling her campaign's new message as she takes on Sanders, who has been popular with young and liberal voters.
UPDATE: 11:22 p.m. EST — Texas Sen. Ted Cruz, who was elected to the U.S. Senate only four years ago and fought off in recent weeks Donald Trump's claims that he is unqualified to serve as president because he was born in Canada, celebrated his hard-fought happy ending Monday night with a good cry. Cruz, with what looked like tears in his eyes, opened his victory speech with a rousing, "God bless the great state of Iowa!" For good measure, he added: "To God be the glory."
UPDATE: 11:10 p.m. EST — Both Hillary Clinton and Bernie Sanders have declared victories in Iowa. But who won? We still don't know. Each campaign has about 49 percent of the vote, with 91 percent of the vote counted.
UPDATE: 10:57 p.m. EST — Republican primary front-runner Donald Trump gave a gracious but stubborn speech Monday night after Texas Sen. Ted Cruz was named the winner of the Iowa caucuses. "On June 16th, when we started this journey, there were 17 candidates. I was told by everybody, 'Do not go to Iowa, you could never finish even in the top 10,'" Trump said Monday. "I said, 'I have to do it.'"
Trump, who has been leading in the polls for months, thanked his volunteers and family members and said he was shifting his focus to the New Hampshire primary Feb. 9 -- where "we're going to be proclaiming the victory, I hope."
UPDATE: 10:50 p.m. EST — Hillary Clinton and Bernie Sanders were locked in a close race in Iowa Monday night with 89 percent of precincts voting. Clinton had 49.9 percent of the vote, and Sanders had 49.4 percent.
UPDATE: 10:45 p.m. EST — GOP presidential candidate Marco Rubio celebrated his third place finish in Iowa Monday night minutes after his longtime rival, Texas Sen. Ted Cruz, was declared the winner. Rubio greeted supporters with his wife and their four children.
“For months they told us we had no chance,” Rubio said. “We are not waiting any longer to take our country back.”
UPDATE: 10:32 p.m. EST — Former Arkansas Gov. Mike Huckabee tweeted from his verified account Monday night that he was dropping out of the Republican race for president. Huckabee had the support of about 2 percent of likely GOP primary voters heading into Monday's Iowa caucuses, which CNN called in Texas Sen. Ted Cruz's favor at about 10:30 p.m. EST.
UPDATE: 10:30 p.m. EST — Texas Sen. Ted Cruz has won the Iowa Republican caucuses with 28 percent of the vote. Donald Trump is in second place, and Marco Rubio is close behind in third place.
UPDATE: 10:10 p.m. EST — With 76 percent of precincts reporting in Iowa, Hillary Clinton had a narrow lead in Democratic caucuses over Bernie Sanders. The Vermont senator had 49 percent support against her 50 percent support. Martin O’Malley was expected to suspend his campaign Monday night after getting 0.6 percent, or six votes, so far in Iowa, the New York Times reported.
UPDATE: 10 p.m. EST — More than 150,000 people were expected to vote during Monday's Iowa caucuses, a huge increase from four years ago when 121,503 Iowans turned out, CNN predicted. A surge in voting was expected to help Republican Donald Trump and Democrat Bernie Sanders, who were both in second place as voting results came in. Marco Rubio was in third place in the GOP contest, while in the Democratic field, third-place candidate Martin O'Malley was expected to suspend his campaign Monday night, CNN reported.
UPDATE: 9:45 p.m. EST — As 55 percent of the Republican vote came in Monday night, Texas Sen. Ted Cruz took 29 percent, Donald Trump claimed 25 percent and Florida Sen. Marco Rubio rose to 21 percent of the vote. Below them, the field remained the same with Ben Carson at 10 percent and everyone else far behind.
UPDATE: 9:39 p.m. EST — With a full 65 percent of the vote in on the Democratic side, the race remained tight between Hillary Clinton and Bernie Sanders. Clinton had 51 percent of the vote and Sanders had 49 percent, while Martin O'Malley had less than 1 percent.
Meanwhile, Republicans were on pace to reach a turnout of 150,000 Iowans, CNN reported. A higher than usual turnout would likely be good news for Donald Trump, who was expected to draw support from new caucusgoers.
UPDATE: 9:14 p.m. EST — On the Republican side, with 22 percent of the vote in from Iowa, Texas Sen. Ted Cruz remained on top with 30 percent of the vote. But Donald Trump was catching up and was at 27 percent, while Florida Sen. Marco Rubio was at third place with 19 percent. Ben Carson held 10 percent, Sen. Rand Paul had 4 percent and Jeb Bush was at 2 percent. Everyone else was under 2 percent.
Hillary Clinton was leading the Iowa Democratic caucuses at 51 percent with 42.5 percent of all precincts reporting. Bernie Sanders had 48 percent support.
UPDATE: 8:56 p.m. EST — With 25 percent of the vote in on the Democratic side, Hillary Clinton had 53 percent, Vermont Sen. Bernie Sanders had 47 percent and Martin O'Malley had 0 percent of the vote, as the Democratic results were coming in much more quickly than the Republican results Monday night. Both political parties have different caucus roles and the GOP has a far larger candidate field.
UPDATE: 8:45 p.m. EST — With 2 percent of the vote in, Donald Trump was ahead of Ted Cruz in the Iowa Republican caucuses with 35 percent of the vote. Hillary Clinton had 53 percent of the vote, against 46 percent support for Bernie Sanders. It’s still very early in the night, but the results saw caucusgoers cheering their candidates’ names at churches, school gyms and other caucus sites.
UPDATE: 8:29 p.m. EST — Republican voters gave no hints as to who they might ultimately pick as the winner of the Iowa caucuses as one of the nation’s biggest nights for presidential politics began Monday. As the caucuses kicked off at Pella, Iowa, GOP voters remained divided over Donald Trump, Ted Cruz and Marco Rubio, The New York Times reported.
“There are a number of candidates I like and one in particular I don’t like — Trump. I’m going to go with Cruz,” Joel Merrill, 61, a forklift mechanic who had never caucused before, told the newspaper. But John Ferrer, 36, who writes for an education website, told reporters he would rally for anyone but Trump, but wouldn’t say who exactly would get his endorsement. “A vote for Trump is a vote for Babylon,’’ he said.
UPDATE: 8 p.m. EST — As the Iowa caucuses began Monday night, voters at a caucus site in Cedar Rapids, Iowa were waiting to hear from both Texas Sen. Ted Cruz and Ivanka Trump, GOP front-runner Donald Trump's daughter. Trump and Cruz have been battling for weeks for first place in Iowa and if Cruz can overtake him, it could help solidify his candidacy this month in South Carolina, Nevada and New Hampshire.
UPDATE: 7:28 p.m. EST — Iowans are arriving at their caucus sites now with just about 30 minutes until start time. Some Republican caucus sites have long lines with several hundred people, meaning turnout could be higher than usual, according to CNN. Turnout is particularly important to the Iowa caucuses because voters determine how many delegates the candidates will send to the national party conventions this summer.
CNN is also reporting that Florida Sen. Marco Rubio's campaign expects a strong third-place showing. Rubio has been in third place in Iowa for some time and a Quinnipiac University poll Monday had him at 17 percent, behind Donald Trump and Texas Sen. Ted Cruz.
With just over an hour left until the Iowa caucuses begin, the 2016 presidential candidates were thanking volunteers, rallying supporters and trying to make sure as many people as possible show up to their caucus locations. Ahead of the voting, the polls showed candidates on both the Republican and Democratic sides in close races that were expected to come down to turnout.
While a Quinnipiac University poll released Monday showed Republican front-runner Donald Trump leading the GOP field as he has for months, the other candidates were not out of the running. Trump led with 31 percent to Texas Sen. Ted Cruz’s 24 percent and he won even more support among first-time caucus goers. But among those who had previously caucused, Cruz received 26 percent support to Trump’s 25 percent.
On the Democratic side, the Quinnipiac poll showed Vermont Sen. Bernie Sanders with 49 percent to Hillary Clinton’s 46 percent, reversing a recent trend that had shown Clinton widening her lead over Sanders in the Hawkeye State. Sanders, who has consistently done well among young voters and those who have not participated in caucuses before, has worked to ramp up his ground game in Iowa, but it remains to be seen if he has done enough.
In 2008, when President Barack Obama saw enormous turnout that helped him upset Clinton in Iowa, he had 37 field offices in the state. Despite some comparisons to the current president’s historic campaign, Sanders has just 23 offices in Iowa, fewer than Obama in 2008 and fewer than Clinton’s 26 offices this year.
“It’s a tie ballgame, that’s where we are,” Sanders said Monday morning, the Wall Street Journal reported. “We will win tonight if the turnout is high. We will struggle tonight if the turnout is low. That’s a fact.”
As the caucuses begin, check back here for live updates and results throughout the night.