What was Rivers Casino thinking? This weekend, when thousands of people were seeking relief in Philadelphia parks from the three-week-long coronavirus lockdown, the Delaware River gambling hall decided to seal off its stretch of the waterfront trail to the public with a high chain-link fence. Joggers and cyclists were forced to loop around the casino’s immense parking lot, then detour onto Delaware Avenue before rejoining the trail south of Penn Treaty Park.

Rivers Casino (formerly SugarHouse) reversed course on Tuesday after pressure from several public officials, and says it will keep the path open from sunrise to sunset. But the brief closure was a bitter reminder that what looks like public space isn’t always public. For more than a decade, the Delaware River Waterfront Corp. has been trying to create an east-side version of the wildly popular Schuylkill River Trail by cobbling together a mix of public and private land.

You now can walk along some sort of paved path from the Columbus Crossing shopping center in South Philadelphia to the former Peco generating plant in Fishtown, a distance of almost 3.5 miles. Although not nearly as crowded as the Schuylkill waterfront, the Delaware trail has come into its own during this crisis. “There’s a steady stream of people walking and jogging at all hours of the day,” marvels Joseph Forkin, who oversees the Delaware waterfront. Ironically, his agency just completed a 900-foot extension that finally links the casino path with the entrance to Penn Treaty Park, making the experience more seamless.

Casino officials say the decision to take their part of the trail out of service was prompted by security concerns. Because Pennsylvania has ordered all nonessential businesses to cease operations, they were forced to shut down the gaming hall. In their minds, that included the landscaped path that runs behind their building. They saw the trail as an extension of their property, not as a public amenity. But it was always meant to be publicly accessible, Forkin says.

Short-lived as it was, the closure couldn’t have happened at a worse time, when outdoor green spaces allow us to escape from the four walls of our home confinement. Philadelphia’s parks are getting a workout like they’ve never experienced before. But so many people are flocking to the trails on the Schuylkill and in Wissahickon Valley Park that it is nearly impossible to walk without being jostled, never mind find the six feet of clear space. It’s social distancing in theory only. And it’s dangerous, says Kathryn Ott Lovell, the city’s director of parks and recreation.

To make more room, the city closed Martin Luther King Jr. Drive to cars last month. But nature abhors a vacuum, and now that wide road on the west bank of the Schuylkill is also being overrun, Ott acknowledges.

It’s not just parks that are swarming; so are the city’s sidewalks. Joggers and dog walkers dip into the bike lanes to avoid getting too close to other pedestrians. We’re seeing a new dance craze: the Corona Swerve.

The incident on the Delaware is also a reminder that our parks could be closed at any time. New Jersey just shuttered its state and county parks because people weren’t following social distancing guidelines. Fearful that crowds could aid the spread of COVID-19, cities around the world are beginning to limit the public’s access to parks. Chicago took the unprecedented action of closing its famous lakefront park and the elevated 606 trail. Paris has banned daytime exercise. London is actually evicting people found in certain of its parks.

But, like the closure of the casino trail, that’s the wrong approach. If we’re going to make it through this crisis with our sanity intact, we can’t stop going outside. Sunshine and exercise aren’t just a natural anti-depressant, they’re known to help boost our immune systems, which is exactly what we need right now.

Rather than close the Philadelphia parks — a nearly impossible task in any case — the city should look for ways to spread people out. One option, Ott suggests, is to get people to visit less popular parks, like Cobbs Creek and Pennypack. “A lot of people don’t know that West Fairmount Park has a 5K trail,” she adds. “We’re working with police and the Streets Department to get some additional park roads closed, so we can continue to space people out.”

The Bicycle Coalition would like to see officials start shutting down more city streets to traffic, so they can be turned into temporary recreation trails. The coalition, which brought the idea of closing MLK Drive to city officials, has submitted a list of possible candidates, says Randy LoBasso, the group’s policy manager. Most are roads that cut through parks. But the coalition is also proposing that the city shut down Rhawn Street between Rowland and Lexington, which would make access to Pennypack Park easier.

Given the demand for space, those closures would just be scratching the surface. Why not turn over a street in every neighborhood to pedestrians and cyclists? That’s easier said than done, according to LoBasso, even though traffic has virtually vanished from some areas. Many city streets are controlled by PennDot, and emergency vehicles still need access.

But the city clearly had no problem closing the 1300 block of Walnut to create a safe zone for the new quarantine site at the Holiday Inn Express. Since buses and other traffic have to be diverted anyway, why not block off the rest of Walnut Street in Center City? It’s not like businesses are open. Turning Walnut into a place for joggers and cyclists could make central Philadelphia feel less desolate than it does now.

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“The weather is only going to get nicer,” LoBasso says. “We can’t be cooped up in houses all the time."

We also can’t keep packing ourselves into the same handful of parks. People are going to keep going outside. If we want them to maintain their six-foot bubbles, we’re going to have to find more places for everyone to spread out.