Hillary Clinton

Democratic presidential candidate Hillary Clinton speaks at a rally at The Ohio State University in Columbus, Ohio, Monday, Oct. 10, 2016.

(AP Photo/Andrew Harnik)

COLUMBUS, Ohio--Democratic presidential nominee Hillary Clinton, pulling away from GOP rival Donald Trump, drew an estimated 18,500 people to a Monday evening rally at Ohio State University - considered to be her largest campaign rally to date.

That's the attendance figure provided by the U.S. Secret Service through Clinton's campaign. Though some reporters estimated a lower crowd count, the rally was unusually large compared to other events Clinton has held in Ohio this election season.

Clinton, speaking the day after the second presidential debate and the day before voter registration ends in Ohio, attacked Trump on a number of issues, most prominently on a report that the billionaire businessman has purchased "illegally dumped" Chinese steel in recent construction projects.

Playing to the younger crowd, she also advocated issues touted by primary rival Bernie Sanders, including eliminating college debt and opposing the proposed Trans-Pacific Partnership trade deal.

Here are five takeaways from Clinton's visit.

The rally was Clinton's largest to date

During past appearances in Ohio and elsewhere, Clinton's campaign usually books venues that accommodate a few thousand people at most.

But on Monday, according to the Secret Service, 13,500 people watched Clinton from inside a security fence, while another 5,000 stood outside the perimeter.

Crowd at Ohio State as @HillaryClinton comes on stage pic.twitter.com/lL21KBdgXP — Jeremy Pelzer (@jpelzer) October 11, 2016

Even if the attendance was lower than that estimate, the rally was different than past Clinton visits to Ohio: it was held outside, at night (after many people got off work). And it had a cooler vibe - celebrity DJ Samantha Ronson, for example, played music beforehand.

Of course, turnout for rallies is an imperfect gauge of how a candidate will do on Election Day - just ask Sanders, who drew thousands to Ohio State in March shortly before Clinton trounced him in Ohio's presidential primary. Trump, for his part, regularly draws large crowds to his events.

But with Trump's campaign in crisis after a video surfaced of him talking vulgarly about assaulting women, and with Clinton leading Ohio in recent polls, the turnout is certainly a sign of the enthusiasm she has here.

Clinton attacked Trump on steel

Renewing an attack she made during Sunday's debate, Clinton went after Trump for using Chinese-made steel in at least two of his last three construction projects. It's a controversy that carries weight in a manufacturing state like Ohio, especially among the white, blue-collar workers Trump has been courting.

Clinton said there was "no justification" for Trump using the "illegally dumped" steel, and criticized his "nerve" for claiming to be on the side of American steel workers.

"It really gets me upset," she said.

Clinton defended her work during the past 30 years

Clinton tried to rebut an effective attack line from Trump that she has little to show during her 30-year career.

"When Donald Trump talks about what I have been doing for the last 30 years, I welcome that," Clinton said.

"Because in the 1970s, I was working to end discrimination and he was being sued by the Justice Department for racial discrimination," she continued. "In the 1980s, I was working to improve the schools in Arkansas ... while he was getting a loan for $14 million from his father to start a business."

She added: "On the day that I was in the Situation Room watching the raid that brought Osama bin Laden to justice, he was hosting Celebrity Apprentice."

Clinton took a page from Bernie

Sanders drew a lot of support from college-aged voters, and Clinton tried to win them over on Monday by espousing many of the issues championed by the U.S. senator from Vermont.

Clinton touted a "joint proposal from Senator Sanders and myself" to allow students from families making up to $125,000 per year to attend a four-year public college or university tuition-free - an idea that predictably got a warm response from the crowd.

She also emphasized her opposition to the Trans-Pacific Partnership. "I oppose TPP now, I'll oppose it after the election. I'll oppose it as president," she said, adding she also wants to find ways to open foreign markets to U.S. exports.

Trump's campaign derided Clinton's visit

Trump campaign spokesman Seth Unger, in a statement released before the rally, noted that despite Clinton's opposition to TPP, leaked speech excerpts show she actually favors "open trade and open borders."

"When Hillary Clinton campaigns in Ohio she pays lip service to an economy that doesn't just work for 'those at the top,' but on Wall Street and in secret paid speeches she promises her fat cat benefactors that her public positions are all for show," Unger said.

"Donald Trump will win Ohio," Unger continued, "because as president he can be trusted to secure our borders, renegotiate bad trade deals that have sent our jobs overseas, and always put America first."