Imagine Stillwater without its Lift Bridge. Go ahead, try.

That’s what most everyone else thought too. And although the old bridge is now permanently retired as a crossing for cars, it stands to live another day — as a pedestrian and bicycle concourse and loop trail.

Once interstate traffic shifted last week 1.5 miles downstream on the St. Croix River to the new, wider and faster four-lane bridge, silence fell over the venerable Lift Bridge.

“That old gal has really served us well. It’s an iconic feature of the Stillwater area — it’s revered,” said Washington County Commissioner Gary Kriesel, a longtime Stillwater resident.

Over the next 18 months, the bridge will undergo changes as it’s restored to its original 1931 appearance.

The familiar gray paint will disappear under a coat of “federal green,” the color of the bridge when it opened. Lampposts of the kind that stood along the bridge all those years ago will appear. Workers will convert the bridge deck into an avenue for people who walk and roll, replacing the pavement with a trail surface.

“The Lift Bridge symbolizes the move of not only Stillwater but the St. Croix Valley into the modern age,” said Washington County historian Brent Peterson. “It separated Stillwater from the lumber era to more of a manufacturing era, from the horse and buggy to automobiles.”

The Lift Bridge will be Stillwater’s launching point for a new 5-mile trail that will loop over the Wisconsin bluffs, cross the new bridge and return to Stillwater along the St. Croix.

The old bridge will be fitted out with new components to keep its lift operating for years to come. One span will be removed next summer to allow boats to pass under while the repair work is done.

All the changes will come courtesy of the $646 million two-state St. Croix Crossing project that built the new bridge. The financing package included cultural and historical improvements, one of which was the Lift Bridge’s preservation.

Todd Clarkowski, who coordinated the St. Croix bridge project for the Minnesota Department of Transportation, participated in discussions beginning in 2002 that settled compromises for the new bridge and led to a decision to preserve the old one.

Stakeholders representing varied interests concentrated on “finding a balance” for the Lift Bridge, he said, and forged a vision: “Keep it in the river valley, make it a recreational amenity, link it to the new river bridge.”

The two-lane bridge — one of the metro area’s smallest and least-traveled — long has enchanted admirers of Stillwater’s charming skyline. But it has also frustrated motorists and merchants forced to cope with long delays whenever the lift went up. Moreover, the bridge closed several times each year for floods, inspections, repairs and general maintenance.

It became a political football, trashed by some people as being on the verge of falling down. MnDOT refuted those allegations, saying that planned repairs would prolong its life. The bridge underwent a $5 million rehabilitation in 2005 and a $3.3 million upgrade in 2012.

Last Wednesday night, a crowd gathered in Stillwater to celebrate the closing of the Lift Bridge to traffic, just as thousands gathered in 1931 to celebrate its opening.

To Peterson, executive director of the county historical society, the Lift Bridge now represents a third era in Stillwater history: tourism.

“That’s what people come to see,” he said. “Without that monument of engineering, I don’t think Stillwater would have the destination clientele that it does today. That lift bridge sets us apart from other river communities.”

Don Empson, another Stillwater historian, wrote that the biggest victory in the bridge debate was preservation of the old bridge.

He quoted Nancy Goodman of the Washington County Historical Society, who wrote of the Lift Bridge in 1999:

“It is sort of the Eiffel Tower of Stillwater. If you can imagine Paris without its tower, you picture Stillwater without its bridge.”