Bedding in tulips in her neat garden on a recent spring morning, she stopped to declare her approval of almost everything the President has done.
“I don’t regret it,” she said. “If the election were to happen again, I’d be making the same decision.”
The 71-year-old is not alone. While Mr Trump’s national approval rating is lower than that of any modern president, a recent Washington Post-ABC News survey found that among those who voted for him, just 2 per cent said they had made a mistake.
Indeed, despite controversies ranging from Mr Trump’s Muslim travel ban, his campaign’s alleged links to Russia and the apparently often chaotic nature of his administration, when The Independent visited Macomb County, it found not a single Trump voter who wished for a do-over.
The vote last November of Ms Ostrowski, a retired executive assistant, was particularly important. Macomb County voted for Barack Obama in 2008 and 2012 by a decent margin. Flipping the county in the 2016 presidential election was crucial to Mr Trump’s narrow 47.3-47 win in Michigan – a margin of just 13,000 votes.
And the New York tycoon’s victory in Michigan became a vital staging post on his way to the Oval Office. Depending on one’s political views, voters here have a lot to answer for.
“The main reason I voted for him was because of his position on abortion,” said Ms Ostrowski. “That was the main thing for me. My only request would that he should not be quite so quick to jump in on things. The seemingly endless townships and anonymous subdivisions of Macomb spread to the north east of Detroit. The population stands at 860,000, of which around 85 per cent is white.
David Marks voted for Mr Trump and said he would score him nine of ten for what the President has done in his first 100 days.
One of the main reasons he opted for the billionaire was that he was not a professional politician, and had promised to shake things up in Washington. “Trump is doing what he can, despite the Congress fighting among itself,” he said, getting out of his car at a strip mall.
He said he hoped the next 100 days would see the Commander-in-Chief press ahead with tax reform. Mr Marks, a retired insurance executive, said that 40 years ago he had been a Democrat but that the party had turned too far to the left and no longer “gave a hoot” about traditions.
“Trump is certainly a character. But I don’t know that we’ve ever had anyone like him in our politics before.”
A 53-year-old woman called Michelle who was raking her lawn, said she was “very happy” with Mr Trump’s first 100 days. She said she approved of his tough talk about building a wall on the Mexican border, his proposal to scrap Obamacare – “One of the most stupid things I’ve ever seen” – and his willingness to threaten North Korea over its nuclear programme. “North Korea – don’t mess with us,” she said.
Mr Trump’s victory over Democrat Hillary Clinton in Macomb County was reasonably easy – and by a margin of around 48,000 votes. He took almost 54 per cent of the here, compared with her 42 per cent. Libertarian Gary Johnson took 3 per cent of the vote with 12,860 ballots and Green candidate Jill Stein took 3,886 votes.
Observers say Macomb County has long been seen as a microcosm of working America and has been a regular stopping off point for candidates seeking the White House.
The county is usually considered to be pro-military, and is the location of the Selfridge Air National Guard Base and a growing defence industrial base cemented by General Dynamics Land Systems and BAE Systems. It is home to many military veterans.
During the 1980s, Macomb County was the political petri dish of pollster Stan Greenberg. He discovered that voters here had voted 63 per cent for John F Kennedy in 1960, but 66 per cent cast ballots for for Ronald Reagan in 1984.
He hatched the name “Reagan Democrats”, and concluded that traditional, white working class voters no longer saw Democratic Party as champions of their interests, but had rather prioritised the concerns of groups such as the very poor, feminist and African Americans.
“My suspicion is that what happened in Macomb is the same as what happened especially across the upper Midwest,” Timothy Bledsoe, a political science professor at Wayne State University, told Michigan Live. “There was kind of a revolt of working class whites who’d been part of the Democratic coalition for years.”
William Desmarais, a military veteran, said he had voted for Mr Trump because “there was no way I could for Hillary Clinton".
“I’m into guns, I’m a member of the NRA [National Rifle Association], I’ve got a CCW [concealed carry weapons] permit,” he said, standing on his driveway.
“[The Democrats] were going to put in place more regulations and restrictions. There are already so many restrictions in place, but people don’t know that.
His neighbour, Deborah Russell, another gardener, said she had voted for Mr Trump because he “had no political background”.
“I think he will run the country, like he’d run a business,” she said. “I voted for him because I wanted someone different – not a politician.”
Asked about Mr Trump’s outbursts and language that many have deemed to be politically incorrect, she said the fact he was “pretty straightforward” was a bonus.
“Sometimes he can say these things, but then so do I,” she said. “He is used to calling the shots.”
Mr Trump campaigned in Macomb County very shortly before the election, holding a rally at the Freedom Hill Ampitheatre in Sterling Heights on the Sunday night before the Tuesday vote.
“Unbelievable what's going on,” he said, in a reference to polls that showed the battle for Michigan getting tighter and giving him the chance of becoming the first Republican to win the state since George Bush Sr in 1988.
“In two days, we're going to win the great state of Michigan and we’re going to win back the White House. We will stop the jobs from leaving your state.”
But not everyone voted for Mr Trump. Lots of people said there was no way they could have supported him and were still reeling from his victory.
Bob Becker, a Vietnam veteran, said the billionaire had won by playing to the fears who felt the Obama administration had “given away” too to people who were undeservedly.
Shawn Miller, an African-American woman, said that given Mr Trump’s “history with women” and his “hanging out” with bigots, there was no way she would have voted for him. As it was, she scored his first 100 days four out of 10.
But Mr Trump had the numbers on his side. In his most vital of electoral battlegrounds, his promise to make American great again, and to restore high-paying jobs to communities that had lost out, won the day.
Jasmine Early, who emigrated to the US from Colombia, said she believed Mr Trump was also going to keep the nation safe.
“People are scared. We don’t want what is happening in Europe to happen here,” she said, a reference to the recent attack in Paris that left a police officer dead.
Dell Gilbert, a 71-year-old retiree, who was shopping, summed up the views of many who had cast their vote for Mr Trump. “I’m happy with what he’s doing,” he said. “I can’t wait to see what’s he’s going to do next.”
And his score for the President? “Oh, it’d be eight or nine.”