Heartening news from the launch of the Green Line is that the newest light-rail train will do what no human could: Create an armistice between two equally fine and prideful cities, whose residents have ignored, or dissed, each other forever.

With street navigation and parking excuses minimized, riders from Target Field in Minneapolis to the Union Depot in St. Paul — OK, from the Union Depot in St. Paul to Target Field in Minneapolis — seem genuinely eager to explore the cultural offerings of their long-lost twin. It’s all good and a long time coming.

But the melting of the Great St. Paul-Minneapolis Divide may not be the most intriguing result. If we commit to taking the headphones off, putting iPhones in our pockets and looking around, we can create desperately needed social traction with far greater reach.

Have you noticed that nobody talks to anybody anymore? Grocery store line, airport security, dinner table. The Green Line can be a green light to change all that.

That’s because people are choosing public transportation in general, and light rail in particular, for myriad reasons. They’re people who otherwise might never meet each other or might not think they’d want to. Now they’ll be sitting, well, cheek to cheek, carloads of multigenerational, socially, economically and politically diverse members of our growing region.

Where else will we get this opportunity to get unwired and chat?

Although the Green Line’s launch was more a party than a predictor of what the train’s daily ridership will look like, it was a hint of what’s possible. The car I rode carried a soft-spoken couple living at the Salvation Army, a former Hennepin County commissioner, young families with strollers seeking museum adventures, millennials seeking sushi, a teenage art student traveling with her mom (and not once rolling her eyes) and a couple from Maple Grove making plans to board again soon.

They fit well into what public transportation gurus identify as the five types of people using these options.

There are, first and foremost, those who have no choice. Christopher MacKechnie, a California-based transportation blogger, calls this group “transit-dependent.” They have no car because they cannot afford one or are faced with physical or mental difficulties that prevent them from getting a license, or maybe they’re no longer driving because of advancing age.

There are “choice riders.” The choice rider has a car, or two, but chooses on occasion to take mass transit, primarily because it is faster or cheaper. Or, let’s admit it, trendy. The choice rider, MacKechnie said, is less likely to take a city bus. They are “very sensitive” to cleanliness, friendliness of the driver and perceptions of safety. “If any of the above are lacking,” he said, “the choice rider will return to driving.”

I like the fact that clean, friendly and safe transit will finally be the norm for transit-dependent riders, too.

Then there is a new brand of rider, called “green” passengers. These riders, mostly young, make enough money to be able to drive, but they choose to live without a car for environmental reasons. They ride bikes and walk and live in the city.

MacKechnie predicts that green riders will dramatically rise in the near future, “as studies show more and more young people with no desire to even obtain a driver’s license.”

Related, but considered a separate bunch, are riders who are savings-driven. How much money can you save making a commitment to public transportation? Lots.

The American Public Transportation Association (APTA) reported in May that transit riders can save $9,000 to $15,000 a year. Minneapolis was No. 11 of 20 cities studied, with public transportation riders saving more than $10,000 annually.

Finally, we’ve got a group of people who simply have had it with congestion. I’m betting that’s a big group. Twin Cities area commuters using public transportation saved 4,152 hours by avoiding road delays in 2011, said APTA spokeswoman Virginia Miller.

With more than 4,000 clearheaded hours added to our lives, we can breathe deeply and, maybe, ask a few clearheaded questions of the person seated next to us:

“What brings you onto the train?” “What’s your favorite bar in St. Paul?” “What are you studying at the U?” “That sounds tough; can I share some resources with you?” “You came all the way from Maple Grove?”

And, most unifying of all:

“Can you believe that gridlock out there?”