There wasn’t always such a clear dividing line between the two neighborhoods on either side of Alter Road.

The change happened slowly. White families began leaving Detroit neighborhoods, a process that accelerated after the 1967 riots. But it took further decades of flight and deterioration for this part of Detroit’s east side to look like it does today. Now, it’s completely different from its counterpart just across Alter in Grosse Pointe Park. That neighborhood still looks much the same as it did decades ago—at least from the air.

Sometimes you can only see the bigger picture from above. This is a current snapshot of what’s become a clear, but very complicated, divide between two cities.

These are two cities, two neighborhoods, divided by one street.

Alter Road is the divide.

To the right, is Grosse Pointe Park.

To the left, the city of Detroit.

Not so long ago, these two neighborhoods on either side of Alter looked almost identical. Dense city neighborhoods with houses packed side by side. With neighborhood schools and neighborhood stores.

But over time, this Detroit neighborhood became one the most blighted and abandoned in the city. And Alter Road became more than a geographic boundary.

It became a racial divide. An economic divide.

As the Detroit side suffered its decline, Grosse Pointe put up barriers. Sometimes literal barriers. See this traffic circle at Kercheval and Alter?

The original plan was to block it off completely. That got scaled back after an uproar. This was in 2015. Instead, they put up this sculpture called “A Sail of Two Cities.” A small gesture toward bridging the divide.

Just down Kercheval are two of Grosse Pointe’s neighborhood public schools. Most of the kids who go here can walk or ride their bike to school. Lots of them do.

The public school on Detroit’s side shut down in 2011. That wiped out one of the last remaining neighborhood institutions. A few years ago, the city of Detroit started a massive demolition sweep through this neighborhood.

It took down scores of blighted and abandoned homes. And it completely transformed the landscape. The homes became vast green spaces. Parts of it feel like the country.

This isn’t just empty space. People still live here, and some of them want to stay. But they’re more and more isolated. Detroit’s leaders are making sweeping, city-wide plans and neighborhood investments.

But it’s not clear what they plan for this corner of the city. Detroit’s new sense of revival has barely touched it.

The Grosse Pointe side of Alter is also changing.

There’s more racial diversity, more different kinds of people in general. It’s less of a bubble. Still, its world remains mostly off-limits to its Detroit neighbors. There’s not a lot of mixing across this divide.

It’s mostly self-imposed. There may not be a real wall along Alter Road, but people on both sides tend to act like it anyway.

This particular divide gets a lot of attention. And you can see why. It’s rare that our dividing lines are so visible and so stark.

This landscape tells a fraught, complicated story about an American city. It’s a story best told from above.