When it comes to the November presidential election, it’s best to think of Pennsylvania as two states.

I don’t mean the ancient east-west division between Philadelphia and Pittsburgh. Nor am I talking about the classic party division of Democrat versus Republican.

What will make the difference in this election – what may decide whether Hillary Clinton or Donald Trump takes this state – is the dichotomy between the Pennsylvania that is prosperous and growing and the Pennsylvania that is stagnant or in decline.

You can use different numbers to tell the same story. Consider population growth: Over the last five years, the population in southeastern Pennsylvania has increased by 110,000, while the population of the cluster of counties around Pittsburgh has declined by 12,000.

Look at manufacturing jobs – a popular topic in this year’s election. If Donald Trump is going to bring back those jobs, he’d better hurry. In the last five years, the Pittsburgh-Johnstown-Altoona region has lost 60 percent of its remaining manufacturing jobs – 141,000 in total. The southeast portion of the commonwealth has lost them, too, but the Philadelphia labor market’s decline has been a less severe 38 percent, or 111,000 jobs lost.

It isn’t new that Pennsylvania is losing manufacturing jobs. We are, simply and plainly, in a post-industrial era. We’ve been losing those jobs for decades. The question for each town and city is: How successful have you been in replacing the factory jobs with New Economy ones, such as education and health care, tourism and business services?

The answer depends, in part, on when you entered the cycle of industrial decline. If you lived in Philadelphia in 1960, you would have had good reason to be optimistic: The population was over 2 million, and the economy had a strong and diverse range of manufacturers. The future looked secure.

We weren’t a one-industry town like Detroit or Akron or Pittsburgh. We were the Workshop of the World, and had been so since after the Civil War.

What Philadelphians could not foresee – what no one foresaw – was the collapse of the entire manufacturing sector that began in the 1960s, and which has yet to find bottom. The ’70s and ’80s in the city were ugly periods of readjustment. It has taken Philadelphia three decades to climb out of that hole.

Not that the city is a wonderland of prosperity today.

A study released earlier this year by the Economic Innovation Group, a nonprofit and nonpartisan think tank, took a deep dive into the Distressed Communities Index of every community in the country, based on ZIP codes.

The study looked at the percentage of residents with only a high school education, the housing vacancy and poverty rates, the percentage of adults not working and the median household income – all measured by the U.S. Census Bureau.

The worse a community did on these measures relative to the national averages, the higher its score.

There were 20 ZIP codes in Philadelphia with distress scores of 75 or above. Clearly, the post-industrial era has not brought prosperity to these neighborhoods. The same was true of neighborhoods in once-flourishing cities like Lancaster, York, Allentown and Reading.

The researchers called this “spatial inequality” – the presence of poverty touching shoulders with stable or prospering neighborhoods. On a map, it looks like a circle of green, with smaller circles of red within.

Philadelphia did not have the highest distress score in the state. That distinction went to Forest County, which lies about 60 miles southeast of Erie. The surrounding country is, appropriately, mostly forest. It has a population of 7,600.

There are other counties in the same end of the state as Forest that are also high on the list: Bedford, Blair, Cambria, Fayette, Indiana and Lawrence, to name a few.

These are areas that once were defined by their steel mills, factories, coal mines and logging operations. Today, those are gone, and no new industries have emerged to take their place. As the population ages, the young must leave town to look for work, and so the vacancy and poverty rates rise.

There are towns in these counties that have a past, but no perceivable future, though it sounds stark to say so.

They are often identified with the industries that made them. For instance, the small town of Crucible, in Greene County, was named for the Crucible Coal Co., which operated mines there. The coal company is gone, but Crucible remains – and it has the highest distress index in the state (99.4), according to the Economic Innovation Group study.

This phenomenon is centered in the west, but not exclusive to it. Pennsylvania is littered with place names that no longer apply or make such sense anymore. The hard coal country in northeastern Pennsylvania, for instance, hasn’t mined hard coal since the 1960s.

Years ago, my then 7-year-old son turned to me during an NFL game between Philadelphia and Pittsburgh and asked, “Dad, why are they called the Steelers?” I started to answer but sputtered to a stop. (It turned out that since Pittsburgh had a baseball team called the Pirates, it seemed logical to him to have football team named the “Stealers.”)

“Change” is a magic word in America. Something to be embraced. It’s also a word that can make many gnash their teeth. To them, the word means loss and decay; it engenders anger and resentment.

It doesn’t take much research to figure out why Donald Trump held one of his big rallies in Altoona, a town in the midst of the anger zone in Pennsylvania. For many, Trump incarnates their desire to smack the powers that be in the face. He also explicitly promises to bring back manufacturing jobs and to revive the coal industry in America. He will summon up the past and make it live again.

The Republican candidate is trying his best to roust these voters and get them to the polls on Nov. 8. It may help explain why, until earlier this month, Trump and Clinton ran so closely in state polls.

There is something to keep in mind as Election Day approaches. In politics, the angry often out-vote the contented.