During a meandering speech, the president, saddled in Washington with sagging job approval numbers, seemed to draw on the energy of his supporters as he made the case that his administration has made "amazing progress" in its first five months.
Despite early setbacks, Trump pledged that he would make good on marquee campaign promises to revamp the Affordable Care Act, cut taxes and spur $1 trillion in new spending on roads, bridges and other infrastructure.
And he sought in Wednesday's remarks to offer a preview of other planned initiatives.
Trump said he will soon introduce legislation that would bar immigrants to the United States from being on welfare for their first five years in the country.
"We'll be putting in legislation to that effect very shortly," he said, drawing enthusiastic applause from an audience of about 6,000 people, according to an estimate by the U.S. Secret Service.
It wasn't immediately clear how Trump's proposal would differ from existing practice. Under a 1996 welfare law signed by President Bill Clinton, legal immigrants must live in the United States for a minimum of five years to become eligible for social aid programs.
Trump also told the crowd that he is contemplating putting solar panels on the wall that he has pledged to build on the U.S.-Mexico border.
"The higher it goes, the more valuable it is," Trump said. "Pretty good imagination, right? . . . We could make it really look beautiful, too."
Trump reportedly made a similar suggestion earlier this month during a closed-door meeting with congressional leaders.
Wednesday night's rally was part of a push by the White House to get Trump out on the road more, speaking to supportive crowds in swing states, where he is likely to get the kind of public adulation that he isn't experiencing much of the time in Washington.
The Iowa trip followed visits over the past two weeks to Ohio, Wisconsin and Florida — official White House trips that featured orchestrated settings where Trump was surrounded by political supporters.
The rally here was the first one staged by his campaign committee since an event in Pennsylvania in late April marking the president's 100th day in office.
Trump bested Democrat Hillary Clinton in Iowa by nearly 10 percentage points in the election last year. He lost Linn County, the jurisdiction in which Cedar Rapids sits, by about 10,000 votes.
Trump was greeted in Cedar Rapids on Wednesday by an "open letter" on the front page of the local paper.
Although it noted that Trump maintains the support of some of those who voted for him, the letter chastised the president for coming to Iowa primarily to hold a campaign rally.
"Mr. President, the campaign is over," said the letter in the Gazette. "You won. Now is not the time to rally. Now is the time to sell your policies, listen to Americans with a stake in those efforts and govern."
Before the rally, Trump appeared at a community college here at an event billed as an opportunity to talk about agricultural innovation. He pledged that he would include a provision in his promised infrastructure package to enhance broadband access in rural areas.
He also reminisced about the support he received from farming communities during the election. "Those electoral maps, they were all red, beautiful red," the president said.
A few hours before the rally started, a couple hundred progressive protesters gathered outside the arena, including several dozen opposed to Trump's decision to defund Planned Parenthood. Several protesters held signs calling for Trump to be impeached.
During his speech, Trump, who has spent much of his presidency at odds with Democrats — often calling them obstructionists — made an appeal to work across the aisle on some of his priorities.
"It would be a beautiful, beautiful thing if we could get together as two parties that love our country and come up with that great health care and come up with that great tax deal for our people . . . and infrastructure and so many other things," Trump said. "Just think about what a unified American nation could achieve."
Wagner reported from Washington.