A river of green runs through it. Seattle as it could be. Patano Studio Architecture

A year ago, Chris Patano stood at the corner of Boren Avenue and Pike Street, looked out over Interstate 5, and began to sketch in his notebook.

Earlier that same day, Patano had left his architecture firm, Patano Studio, and walked up Pike Street, through the soulless glass canyon of the convention center and then along the concrete walls of Freeway Park. When he got to the windswept Plymouth Pillars he turned toward Boren Avenue. Where there were once homes, shops, gardens, and a grand stairway called the Republican Hill Climb that connected South Lake Union to Capitol Hill, today there is a canyon filled with cars.

As he walked, Patano stared down into the freeway's canyon and then up at the cranes raising new skyscrapers alongside it. As an architect specializing in parks and public spaces, he was used to filling in gaps, to seeing possibility in empty spaces. But the potential of I-5 had always eluded him—a massive scar that cut the city in half, I-5 was simply too overwhelming a void.

That day, though, he began to see the possibilities. Behind the Paramount Theatre, he saw a green hill rise, with switchbacks for bike paths. Above a soon-to-be-decommissioned bus station, a green roof concealed the ever-expanding convention center. Stretching up past Re-bar and the Facebook tower, a winding green meadow capped the freeway. Cars would pass underneath, unseen and unheard, as residents strolled, picnicked, and settled in to watch the sunset.

"I could finally see it," Patano told me when I met him at his office, several months later. He gestured to a wall covered with thumbtacked schematics and diagrams and 3-D models. "But we need to do it now. Or the moment will pass."

Our city is experiencing its biggest boom since the gold rush, but the resources and drive to build dreamy projects won't last forever. Patano knows from bitter experience what happens when Seattle lets opportunities like these pass by.

It's been 60 years since the east and west sides of Seattle truly touched.

"This area contains older and less desirable buildings," planners wrote in 1957 of the freeway's path. That quote was unearthed by urban designer Scott Bonjukian, a longtime proponent of lidding I-5. When they drew the highway's path of destruction, state officials noted, "From Marion Street to Denny Way, this section will traverse an area that needs improvement in appearance."

Their idea of improvement? A deep, noisy ditch filled with cars.

And their idea of public hazards? Anyone who wasn't in a car. When the grand staircase that connected South Lake Union to Capitol Hill was destroyed in 1957, shortly after construction of I-5 began, a city engineer triumphantly wrote, "Pedestrians, who are a constant hazard to city driving, are entirely removed."

The idea of capping I-5 with a park isn't new. World's Fair architect Paul Thiry suggested a lid before the freeway was even built. And every couple of years, an ambitious grad student or planner or blogger (or all three) drafts a plan to rejoin the city's severed neighborhoods. It never goes far—because of the cost.

Patano Studio Architecture

But the cost of Seattle's uncovered freeway is immeasurable. There's the obvious mangling of Seattle's quality of life—accounts from the 1930s describe Capitol Hill residents strolling down to Lake Union for summer morning swims—but there's a far grimmer toll. A map from the Washington State Department of Health shows that "cancer risk attributable to on-road sources" is low throughout the city, with the only exception being a hot-pink cancerous river that traces the routes of our exposed freeways. Chances are good that you or someone you know will suffer—or has already suffered—a stroke, heart attack, or cancer exacerbated by I-5.

Chris Patano grew up on a river near Coeur d'Alene, and he moved to Seattle in the mid-1990s with an architecture degree from the University of Idaho. His first publication in Architectural Record was a design for the Seattle Commons, a proposed park that would have extended several blocks south from Lake Union—a proposal rejected by voters, twice. (The Stranger opposed the Seattle Commons on the grounds that it would have turned over too much control of the neighborhood to wealthy developers. Good thing that didn't happen.)

Upon his arrival, Patano lived in the Belroy Apartments on Bellevue Avenue, overlooking I-5. Soot from all the cars would accumulate on his windows when they were closed, and in his home and lungs when they were open. And then there was the noise.

"I tried to imagine it was flowing water," he said.

Twenty years later, Patano is still imagining what else the I-5 trench could be. Since that walk last spring, his firm has developed a proposal for a 45-acre park that would serve as a roof above the freeway, with a convention center, a hotel, and an arena folded into the park. In his proposal, there's room for parking, affordable housing, and nearly 300,000 feet of office space. Renderings show the freeway vanishing beneath bustling city activity.

Parks have been built above freeways all around the country: There's one in Dallas, one in Duluth, and another in Columbus. If those cities can do it, Seattle can too. In fact, Seattle has done it already—twice.

The construction of Sam Smith Park covered several blocks of Interstate 90 with playgrounds, homes, and businesses, while creating a scenic vista—precisely the elements destroyed to make room for I-5. And on Mercer Island, a park conceals another I-90 stretch. "We don't want to see it," demanded Mercer Island mayor Aubrey Davis, after whom the park is named, when WSDOT was planning a freeway expansion in the 1970s. "We don't want to hear it. We don't want to smell it." In response to Davis's pressure, the state changed its design, constructing a lush green lid to accommodate the mayor's demands.

I asked Patano if he'd ever seen the 1992 movie Singles, in which a Seattle planner dreams of a "supertrain" to connect the city's suburbs. In the film, Mayor Tom Skerritt rejects the proposal. "People love their cars," he says, sending the planner into a depression that can be solved only by Bridget Fonda, torn denim, and Alice in Chains.

Patano smiled at the reference. "That's my generation," he said, and we both agreed that the mayor may have been right, at least for the time. It certainly seemed in the early '90s that Seattle would never embrace rail—and yet, after a decade and a half of bitter dispute, the Central Link line opened in 2009. In a few months, light rail will expand to Capitol Hill and the University of Washington. Mayor Ed Murray believes wholeheartedly in rail, and this November, we'll be voting on the Sound Transit 3 proposal to expand trains even farther. Something has changed.

People certainly did love their cars when the freeway was built. They loved them in the 1990s, when the city was locked in a dispute over light rail. They loved them as recently as 2009, when our leaders developed a what-could-go-wrong plan to replace the Alaskan Way Viaduct with a high-traffic tunnel.

But Seattle's priorities have changed.

"The density of the city finally reached a tipping point," Patano said. His proposal is currently floating around the offices of various city council members, the mayor, and neighborhood councils, with reaction ranging from enthusiasm to cautious curiosity.

The project's next phase, a more detailed analysis, will require $300,000 to $500,000 in funding. Building the thing, of course, will cost billions. But the I-5 corridor is in desperate need of repair, and compared to the cost of needed roadwork, the price of adding a park—and knitting the city back together—would amount to a tiny fraction.

For the moment, we're still stuck with an I-5 that cuts off communities and slowly kills us. But when he looks at the freeway, Patano said, "I can now see what should be. I see what it could be. Trails and trees."

Walking back up to Capitol Hill after our meeting, I stopped on Olive and looked out over I-5. The onslaught of traffic was overwhelming, and try as I might, I had difficulty summoning a vision of picnics and paths in place of concrete and fumes.

A family with a young child walked past me on the sidewalk, the kid holding a sippy cup that he clanked back and forth along the railings like a prisoner in a movie. As he walked, the kid stared at the freeway underneath. I wondered if it was easier for him to imagine something better. recommended