DES MOINES, Iowa — The Iowa State Historic Museum went from virtually deserted at 6 p.m. Monday to teaming with about 1,000 caucus-goers by 7 p.m, all of them streaming into one of six precincts — three Democratic and three Republican — as the Hawkeye State officially kicked off the 2016 presidential campaign.

By 7:30, Precinct 55 Democrats in the museum’s Cowles-Kruidenier Auditorium had so packed the 500-capacity venue that all observers were asked to leave. By 8:15, the chants of “Bernie! Bernie! Bernie!” came out.

In the first round of voting, Sen. Bernard Sanders of Vermont had secured 238 delegates, Hillary Clinton 183, former Maryland Gov. Martin O’Malley 24 and 10 were undecided. There was then another round, where Clinton and Sanders supporters tried to woo people to change their mind. In the end, organizers did the math and they announced a split decision: Five delegates to Sanders, five to Clinton.

It was a night of incredibly tight margins: Clinton and Sanders were separated by 1 point for much of the evening, while Ted Cruz finally pulled away from his rivals. And it was a night of disappointments: O’Malley and Republican Mike Huckabee suspended their campaigns. The scenes playing out in this Des Moines museum reflected the raw form of democracy that helps shape the presidential nomination process every four years.

“Happy Caucus Day.”

One heard that a lot on Monday, the occasion of Iowa’s first-in-the-nation presidential caucuses, as the state, and the world, tuned in for the first official contest of the 2016 race. But for all the hullaballoo attached to the state’s role in weeding out some of the most ambitious political figures in the United States, for many Iowans, it’s a day like any other.

It’s not even a state holiday.

“I still have to take my my kid to swim practice tonight,” said Chris Haines, an artist and employee of the Iowa Department of Cultural Affairs. “I would have thought they would have cancelled it, but no.”

At the entrance to the museum here is a 150-pound, six-feet diameter, spun aluminum Rand McNally globe of the earth that graced the lobby of the Des Moines Register & Tribune Company from 1950 to 2013. At its base it states simply: “Bringing the World to Iowa.”

It’s hard to think of a more appropriate entry marker for the museum, which sits across the street from the state’s neoclassical-style capitol building and hosts those six caucuses.

The media contingent in town resembles nothing short of a small army, easily identifiable by press credential lanyards and television satellite trucks lining downtown and especially Locust Street, which provides a straight shot for cameras eager for a stunning standup backdrop.

Yet many Iowans seem to be nonplussed, but focused, about the night’s activities, perhaps a result of studied preparation. Haines, a Clinton supporter, said he and his fellow precinct cohorts in his nearby town of Johnston who are in the Clinton camp had been instructed on strategic options.

“As Hillary supporters, we’ve been instructed to, if we see it slipping away, to go over to O’Malley,” he said, who is running a distant third to Clinton and Sanders.

On the Democratic side, caucus-goers meet and form groups that rally support for their preferred candidate. This includes trying to convince other participants to change sides. If a candidate does not reach a 15 percent threshold of support, he or she is considered “unviable” and is removed from the process.

At that point, those supporters can choose to go over to another candidate’s side, and a second tally is taken to determine how many delegates are awarded to the “viable” candidates. Those results are then reported to the state party, which releases the percentage of delegates won by each winner, not the popular vote.

The thinking is that if Clinton is losing a particular precinct to Sanders, it would be better for her supporters to go en bloc to O’Malley and siphon his delegates away to a candidate who has less of a chance of winning the state.

“Last day panic is what it smells like,” Haines said.

The Democrats also discuss and decide on resolutions unrelated to presidential candidates, such as one put forth by Iowans for D.C. Statehood that calls for citizens of the nation’s capital to have full representation in Congress as a state.

Shadow Sen. Paul Strauss, a Democrat elected by D.C. voters to argue for statehood and equal rights for the District, was granted permission to address the Democratic precincts at the museum. “It was a very moving experience to share with these people who are so excited to be a part of democracy that, sadly, we can’t,” Strauss said.

The Republicans have simpler rules. People stand up, deliver a speech for their candidate, then everyone votes by secret ballot, and the totals are reported to the state party, which releases the tally.

“I think this is the last stand to talk about issues,” said Adil Khan, who was speaking for Sen. Rand Paul, R-Ky., in the GOP’s Precinct 55, on the third floor of the museum. This was Khan’s third caucus. He supported Paul’s father, former Rep. Ron Paul, R-Texas, in 2008 and 2012.

“At least I got one other person with me,” said Will Hunemuller, another Paul supporter, looking across the room in vain for more visible Paul support. This was Hunemuller’s second caucus. He supported the candidate’s father in 2012.

Ivette C. Lozano, who said she came to Iowa from Dallas to rally support for her home-state Sen. Ted Cruz, R-Texas, was excited. “I’m about to convert 400 people in this caucus room to Sen. Ted Cruz.”

Meanwhile, across the street from the museum is the Des Moines district office for Rep. David Young, R-Iowa, the freshman congressman who was previously chief of staff for Sen. Charles E. Grassley. Just a few hours before the caucuses started, the office was quiet. They don’t get too many calls and requests from constituents with frequently asked questions about the process.

There was no mad rush among the staff, who were quietly going about their business in the afternoon. Young himself was back in Washington, owing to the House going back into session. Ditto for Grassley, who, despite doing nine campaign events over the last four days, including one early Monday morning for Paul, wasn’t about to miss his first vote in more than 22 years.

For Haines, he left work around 4:30 p.m. His precinct in Johnston is in a barn. After caucusing, he had to head back to the museum to help break down the site’s caucuses’ set-up. It’s all in a day’s work in a state that takes its civic engagement seriously.

“It’s very Iowa,” he said.

Contact Dick at jasondick@rollcall.com and on Twitter at @jasonjdick.