JACKSON, Michigan – Did Mitt Romney win the Michigan primary? Or did he merely survive it? That really depends on your perspective.

As recently as a few days ago, Romney was trailing in the polls. And as recently as Tuesday afternoon, Romney staffers were talking down expectations. But Romney won a clean victory on Tuesday night. He won handily in the Detroit metro area, his home turf, but he also ran strong in more contested counties, like Livingston and Jackson, to the west.

But why was it ever this close? Romney had superior money, organization, and, for a long time, name recognition. This state ought to be friendly to him – not because of his family ties, which were never as important as pundits assumed, but because the economy is the biggest issue in Michigan and Romney bills himself as the candidate best positioned to deal with it. Instead, Romney had to fight off an insurgency from Rick Santorum, who appealed to economically strapped voters by appealing to their cultural values.

Romney succeeded, but the exit polls suggested a familiar class divide. Romney won among voters who attended at least some college and those making more than $100,000 a year. But he lost among voters who attended no college and among those making less than $100,000 a year.

As New York Times economics guru and Washington bureau chief David Leonhardt tweeted, if you genetically engineered the typical Romney voter, it was a single Catholic woman who was older than 65 and with a household income of more than $100,000.