A promised bridge over the Mystic River would be a missing link for Somerville and Everett. So where is it?

Two governors have committed to build a footbridge across the Mystic to the Encore for pedestrians and cyclists, one of the largest such crossings in the Boston area.

But years later, it’s become a very Massachusetts kind of project: Construction has yet to begin and no one can say when it will. Indeed the public hasn’t seen a building plan for the new footbridge since 2021, when they first glimpsed renderings of a bridge plan that has since been put back on the drawing board.

The billions of dollars of new development on each side of the river, and the state’s efforts to promote car-free travel, make the gap all the more glaring an omission.

State officials insist they’re hard at work. The Department of Conservation and Recreation last week said it and MassDOT are still finalizing the design for the bridge, which spokesperson Chloe Gotsis described as “a critical link” in the region’s trail system.

The redesign, Gotsis said, will allow the agencies to consider feedback from cycling advocates who have urged the state to widen it from 12 feet to 14 feet to better carry walkers and cyclists at the same time. And the state, she said, is weighing other changes as well to make the bridge easier to build and maintain.

If and when it’s built, the impact on cycling in the region will be huge, said Tom Lamar, chair of the Somerville Bicycle Committee, because crossing the river without a car can be harrowing.

“The Mystic River is just this tremendous barrier right now,” Lamar said. “The individual pieces coming together in that area are great, but the gaps between them are just awful.”

Cyclists taking new bike paths and pristine protected bike lanes near the casino find they give way to a busy four-lane highway that crosses a drawbridge with a metal grate and then feeds into the gargantuan rotary in Sullivan Square.

“You’re very close to high speed traffic,” he said. “On the drawbridge, it’s slippery. It’s very easy to slip on in the rain. It’s pretty, pretty scary.”

The other white-knuckle route, to the north, is the Wellington Bridge, which offers cyclists a painted lane separated from, but still close to, traffic.

Either way, “it’s not really a comfortable biking connection,” Lamar said. “So this bridge is going to be a game-changer.”

Closing the gap, bike advocates say, will go a long way to convincing otherwise wary cyclists to consider hitting the bike path, either for fun and exercise, or as a reasonable, safe, even pleasant way to commute.

Somerville’s neighbors from Everett to Lynn have been enjoying a separated bike trail that follows old train tracks past dozens of parks, cuts through picturesque marshland, and will one day travel all the way to the beach in Nahant.

It’s a shame that once it gets to the cusp of Somerville and Boston it “just ends,” said Jonah Chiarenza, a Melrose cycling advocate. “You have this incredible asset that the state and the cities of Everett, Malden, Saugus, et cetera have invested in, and it just dumps you out into one of the biggest rotaries in Boston,” he said.

Gotsis said the projected cost of the bridge remains $49 million, the amount estimated for the old design that called for a grand, curved 785-foot-long suspension bridge.

The state, she said, will pay for most of it as part of its five-year capital plan, and the state Gaming Commission will kick in $650,000. The company that owns the Encore, which helped pay for the original design, has not committed to contributing to the cost of construction. The Baker administration said in 2021 it would pursue a federal grant for the project, but that didn’t materialize.

When a bridge might be finished is a mystery: Once the new design is released, it will be subject to another public review, then a bidding process, before construction can begin. State officials declined to estimate when that might be.

More than a decade after Assembly Row opened, and almost five years after Encore threw open its doors, there are other loose ends as well. It’s been an open question whether any changes might be coming to the Assembly MBTA stop, which is only accessible from Assembly Row, with the T tracks in the way of the riverfront.

To get to the proposed bridge, T riders would have to take a roundabout walk of a half-mile or so. MBTA spokesperson Joe Pesaturo wouldn’t say if the agency considers it a priority to add an east-facing exit to the stop, which opened in 2014.

If delays continue, the absence of a bike- and pedestrian-only link across the Mystic may be even more apparent in the coming years.

Work on a planned renovation of Draw Seven Park, the now largely neglected grassy area where the Somerville side of the proposed bridge would be built, is set to begin this summer.

New features on the Everett side may be coming soon, too, including an expansion of the casino’s entertainment offerings across Broadway and a possible soccer stadium just down the road.

Still, that’s no reason to rush, said Chiarenza.

“It’s a generational investment,” Chiarenza said. “It will hopefully be up for 50 to 75 years. It’s worth another couple of years to get it right.”

Everett Mayor Carlo DeMaria, who shepherded the arrival of the Encore casino, sounded an optimistic note on the ongoing saga.

“There are just a couple issues that need to be worked out, and I believe they will be worked out and we’ll get it resolved,” he said.

Among transportation priorities for the city, he ranks the bridge up there with a proposed extension of the MBTA’s Silver Line through Everett and a hoped-for commuter rail stop. The crossing would be the most direct access many residents and workers have had to an MBTA station, as well as the final leg of a community path that dates back to 2008.

“The last piece, basically, is the bridge,” DeMaria said. “So for us it’s hugely important.”

Spencer Buell can be reached at spencer.buell@globe.com. Follow him @SpencerBuell.