When light-rail trains begin picking up riders Saturday in St. Paul, the city will enter the realm of 21st-century transit using the basic technology it rode to prosperity more than 100 years ago: rails.

It's hoping that a similar boom results, in ways both tangible and symbolic.

From the Union Depot, the newly renovated train palace overlooking the Mississippi, to the State Capitol and then along University Avenue — the ancient path of ox carts and streetcars — the Green Line is said to represent St. Paul's best shot in years to turn around a stagnant downtown and revitalize what was once the Twin Cities' busiest strip.

Of the $2.5 billion in investment that the Metropolitan Council credits in part to the 11-mile Green Line (7 miles of which is in St. Paul), $681 million is for current or planned projects in downtown St. Paul and $218 million is for projects in the Midway district from the city line to the Capitol.

Mayor Chris Coleman said downtown and University Avenue already look different: "The rapid change that we've already seen and the investment that's already occurred, I think, has been pretty striking." The Green Line is significant in other ways for St. Paul. The $957 million project not only underscores University Avenue's historic role as the oldest link between the Twin Cities, it recasts University as a gateway for the city's neighborhoods, ethnic dining, music scene and sporting events.

The line will make it easier for nearby residents, many making low to moderate incomes, to reach jobs elsewhere. And it simplifies travel to St. Paul's many colleges and medical centers, as well as the state government.

"More and more people are getting exhausted with the automobile," said John Diers, a former Metro Transit superintendent who has written histories of the Union Depot and the local streetcar system. "I don't predict the suburbs are going to be abandoned anytime soon, but with light rail you're going to see much more attention to St. Paul."

LRT as game changer

It took longer than expected. Back in the 1990s the Central Corridor — the popular name for the line before Metro Transit gave it a color — was widely thought to be the best place for the region's first light-rail line, given its ridership projections.

But St. Paul proved unable to top the strong case made for the Blue Line, which could run on land along Hiawatha Avenue and link downtown Minneapolis with the airport and Mall of America.

Now, 10 years after the Blue Line opened, it's clear that building another line in the west metro would have been disastrous for St. Paul, said Nancy Homans, Coleman's policy director.

"It would have been like the towns that died on the prairie when the railroad passed them by," she said. "The region would have developed to the west."

What makes the line a game changer, said St. Paul Area Chamber of Commerce President Matt Kramer, is its convenience and reliability. "For the first time people can stay in St. Paul and get on the train to go to anything," he said.

Coleman agreed. "The Super Bowl comes to Minneapolis, and you have now a direct link from downtown St. Paul on a first-class transit system that will take you right to the front door of the stadium," he said. "It connects us in a way that we probably haven't been since streetcars, but in a much better way."

The trail of the 'Interurban'

Connecting St. Paul and Minneapolis with a road was considered so important in the 1870s (and a natural step toward what people thought was the inevitable merger of the two cities) that the Legislature ordered it done.

University Avenue — named for its proximity to the University of Minnesota and Hamline University — has been there since.

By 1891, electric streetcars rumbling along University between the two downtowns had replaced horse-drawn trolleys and commuter trains. The "Interurban" streetcar line was one of the busiest in the Twin Cities, said local historian and nonprofit leader Brian McMahon.

"Commercial nodes grew up around the trolley stops, where the lines intersected each other," he said. "So along University the natural spurts of development were spaced about a mile apart. That is essentially where the new stations are today."

Spurred by suburban growth and the postwar boom in automobiles (and what some consider an unholy alliance with General Motors), buses began replacing streetcars in the 1950s.

The last streetcars ran in St. Paul in late 1952; within two years Minneapolis also had converted to buses.

In the 1980s, St. Paul Mayor George Latimer tried in vain to get federal funding for an elevated "people mover" in downtown. "It was a disaster we avoided through sheer luck," he says now. "It would never have been able to accomplish what we now have emerging with the Green Line."

When officials talked in the 1990s about building a transit line between the two downtowns, the reasons cited were to cut fuel consumption and lure investment. University Avenue was chosen over Interstate 94 because of the potential development, and trains chosen over buses because they would draw more riders, cost little more to operate and were expandable.

Unusual in several ways

The resulting line became the biggest public works project in state history.

It's unusual in several respects. It never once ventures off streets, bringing trains closer to vehicle traffic far more than the Blue Line — which may account for four collisions and other close calls that test trains have had since last winter.

No park-and-ride lots were built, after a St. Paul study showed there was more than enough parking on University, nearby lots and cross streets. And Metro Transit had to provide vibration-absorbent tracks near the U and Minnesota Public Radio to protect labs and studios.

The process used to build the line was pure St. Paul, shaped around grass-roots activity that sometimes failed (legal efforts by a coalition of black leaders to halt the project due to feared negative impact) and sometimes succeeded (residents' demands for three more stations).

City leaders, remembering how I-94 ripped out the predominantly black Rondo neighborhood in the 1960s, offered forgivable loans to shops that lost business during construction. More than 100 businesses either closed or moved from 2011 through 2013, while 128 businesses opened at the same time.

Hennepin County Commissioner Peter McLaughlin, one of the metro area's leading transit advocates, said the Green Line is emblematic of the Twin Cities' new emphasis on itself as a single regional economy, rather than the traditional model of two cities duking it out for limited spoils.

"People have asked me, 'You're from Minneapolis, so your big competition is St. Paul, right?' And I say right — Sao Paulo, Brazil," he said. "[The Green Line] really does say we're starting to build the transportation system we need to be competitive in the world."

Peter Bell, who was chair of the Met Council when the line was planned and approved, said he thinks "it will enhance people's feelings that the Twin Cities is a region."

He added: "There is no major metropolitan area on the planet that doesn't have a vibrant transit system. That is part and parcel of being a major urban center."

Kevin Duchschere • 651-925-5035