When talking with people who advocate for ripping out rather than rebuilding Interstate 94 in St. Paul, there's always a nagging thought running through my head: "Can they really be serious?"

People living near the freeway sure think it's an idea worth considering, said Alex Burns, program coordinator for Our Streets Minneapolis. That's what they heard in the advocacy group's door-knocking efforts along an 8-mile stretch of the I-94 corridor between the downtowns of Minneapolis and St. Paul.

"Even if they use the freeway, they understand most of the harms," Burns said.

The I-94 freeway was part of the interstate highway system, a massive investment in transportation infrastructure that was partly justified by 1950s-era national defense worries.

We have different worries now. We need to have different priorities for transportation investments.

There will be a cost for taking I-94 out, and not just paying for the removal and filling in part or all of the "trench" through St. Paul where the roadbed lies. Just like water continues to flow around a rock dropped into a stream, I-94's car traffic would flow somewhere else.

The real question is whether the benefits justify the costs and who's truly going to benefit.

There's plenty of evidence that investments in transportation do boost productivity if it really does get easier and cheaper to move people and goods around.

Better transportation means more efficient companies by allowing them to buy less expensive services and materials from a broader array of suppliers. They can recruit from a much larger talent pool, just as workers can consider jobs at a lot more workplaces without having to move.

In the Twin Cities, that might mean that the 3M Co. — just east of St. Paul — might recruit a great candidate living in the western suburbs of Minneapolis. It won't always be fun to drive twice daily straight through Minneapolis and St. Paul, but it's doable.

One idea that's been floated: shut down I-94 for the 3-mile stretch between the Allianz Field soccer stadium and State Capitol exits. This vision is partly motivated by the idea to restore the Rondo district west of downtown St. Paul. Those neighborhoods were home to about 85% of St. Paul's African American families before the freeway was built.

By the time this section of I-94 opened in 1968, hundreds of Black families had been displaced.

Others have argued that it would be best to remove the entire stretch from near downtown Minneapolis all the way to the current hookup with I-35E on the edge of downtown St. Paul.

That theoretical commute from suburban Minnetonka to 3M's Maplewood campus would get a lot longer and more costly.

Some people will almost certainly turn to public transit if I-94 closes, but one of the ironies is that the transit users hoping to quickly get from downtown Minneapolis to downtown St. Paul now usually jump on a Route 94 express bus. This freeway bus is a lot quicker than the light rail train, which has to stop at traffic lights and transit stations.

The history of I-94 in St. Paul seems to still matter a lot. Early on, there was a thoughtful alternative to where it ended up, along St. Anthony Avenue in St. Paul. This idea put it a little to the north and in an existing rail corridor.

That would have meant much less disruption to the city. The State Capitol area wouldn't have been cut off from the rest of downtown St. Paul. And it would have spared Rondo.

One of the local participants during the post-World War II construction era, longtime city of Minneapolis official Tommy Thompson, appeared in a 2017 Twin Cities Public Television and MnDOT documentary on I-94. He said they knew about the German system of autobahns — expressways that enabled quick car trips between cities, but that didn't go into German cities.

The problem Thompson and his colleagues needed to solve was traffic congestion inside Minneapolis. Car ownership was booming.

Back in 1950, the metro area was just Minneapolis and St. Paul, together with more than 70% of the seven-county metropolitan area's population. Suburban counties like Washington, Anoka and Scott were still rural.

Maybe the social engineering was unintentional, but these new freeways made it feasible to live way out of the city and still quickly drive into the city for work, attend ballgames and so on.

This easier movement in and out of the central cities came at a big cost to them. The population has fallen since 1950 in both Minneapolis and St. Paul, and together they now hold just a small fraction of the region's population. Meanwhile, the population of Washington County in the east metro has grown nearly eightfold since 1950.

Folks working on the issue of rebuilding I-94 call it "the trench" because of the valley it carved into St. Paul that's about the length of a football field wide and runs for miles, restricting the easy flow of people between neighborhoods. An analyst last week called the freeway in St. Paul a "pollution sewer" of noise, car exhaust and other pollutants.

Few things look great on a gray Minnesota day in December, but the view from one of the St. Paul bridges crossing I-94 is irredeemably ugly.

Other cities have begun removing their urban freeways. A well-known project in Rochester, N.Y., took out a short section of what was known locally as "the moat."

That's a point that Burns of Our Streets Minneapolis made: one opportunity cost of rebuilding I-94 as a conventional freeway is giving up the kind of tree-lined, people-friendly boulevard like the one built in Rochester.

When he's talking about removing I-94, he's really talking about its replacement by a broad boulevard. The barrier between neighborhoods would be gone. There would be room for cars, bikes, rapid transit, kids to push along on their scooters, green space and lots of sites for new housing and other development.

Instead of a noisy, smelly eyesore built and maintained to get cars through town quickly, the corridor could be a Twin Cities jewel.

A region that's much less dependent upon car traffic sounds great to Jonathan Weinhagen, president of the Minneapolis Regional Chamber of Commerce.

Yet it still doesn't sound at all practical to him to rip out a major regional artery for automobile traffic.

Weinhagen sounded concerned that the conversation over what to do with I-94 will split cleanly into two sides. One, committed to cars, will want not much more than reconstructing I-94 to expand capacity. The other will hope to see the highway gone altogether.

He's looking for a middle way, describing "future proofing" the design for reconstructing I-94. That suggests making sure it's easier to adapt this public asset to different kinds of transit or land use practices as they emerge.

And he added what everybody else mentioned, too: Another opportunity to rethink the I-94 corridor won't soon come around.