In graphics: How Trump conquered the industrial and Democratic heart of the US

Donald Trump visited 29 cities in historically Democratic Michigan, Wisconsin and Pennsylvania during his campaign. Hillary Clinton visited only 10 of the cities, and never visited Wisconsin. Compared to 2012, the Republican president-elect gained votes in most of the counties in the three states –202 out of the 222 counties, or 91 percent. That was especially important in Wisconsin, where votes from the large number of rural communities eclipsed the Democratic votes in densely populated Milwaukee, Waukesha and Dane Counties.

In Michigan, Trump increased his votes in large urban counties like Wayne (Detroit), Macomb and Genesee (Flint). He did the same in Pennsylvania in Philadelphia and Luzerne, but not in Allegheny (Pittsburgh).

Trump won all three states with just 107,000 votes

With the drop in votes for the Democratic candidate in Michigan, Wisconsin and Pennsylvania, Trump needed a mere 107,330 votes to claim victory in all three states, with a total of 46 electoral votes. The three traditionally Democratic states were crucial to a Clinton win.

The collapse of the Democratic Party

Although the gap in vote totals for Trump and Clinton in the three states was relatively small, a comparison with the 2012 presidential elections shows the number of votes for the Democratic candidate last week fell by 681,540 while the number of votes for the Republican candidate rose by nearly 400,000.

Reasons for the GOP victory

The reasons can be put into two categories – those that helped Trump and those that harmed Clinton. Exit polls showed that dissatisfaction with the direction of the country among the non-Hispanic white majority (more than 75%) and a desire for change were the keys to the Republican victory.

Some analysts say that part of the dissatisfaction was the result of the economic woes in the so-called Rust Belt. That's where the manufacturing industry – steel mills, automobile plants, etc. – lost hundreds of thousands of jobs since the 1990s.

Some of the jobs returned in the last few years, but mostly in the leisure and hospitality sectors that generally offer lower salaries. Charles Ballard, a Michigan State University professor, said Trump “played to that [economic] anxiety very skillfully throughout the industrial heartland of America, and won Ohio, Pennsylvania, and Wisconsin, as well as Michigan.”

During Trump's repeated visits to the three states, he promised to bring back jobs by canceling free trade treaties, which he blamed for pushing U.S. jobs to other countries. Michael Berkman, a professor at Penn State University, said that “definitely there are areas that Trump campaigned harder and had a compelling message.”

For Ballard and Berkman, the economy was not the only reason for the GOP victory. Trump also had an effective anti-immigration message, and won almost all the counties with white majorities. “In Michigan as elsewhere, Trump's appeal to racial resentment and xenophobia was very powerful among ethnocentric whites,” said Ballard.

What hurt Clinton

One of Clinton's biggest problems was the Democratic voters in Michigan and Wisconsin did not vote for her in the party primaries. Ballard noted that Sen. Bernie Sanders' victories in those contests “was clear evidence of dissatisfaction with Clinton among Democrats.”

Polls before the election regularly showed Clinton leading Trump, perhaps one of the reasons why the Democratic candidate did not travel much to the three states. Benjamin Marquez, a professor at the University of Wisconsin-Madison, said Clinton did poorly reaching the working class in Wisconsin – a state she did not visit during the campaign.

University of Wisconsin-Milwaukee professor Kathleen Dolan said that among other possible factors for Trump's victory in Wisconsin was the voter ID-law approved this year that may have pushed down the turnout among minorities, who tend to vote Democratic.

Alejandro Fernández Sanabria and Javier Figueroa contributed to this report.