Urban planners came to Denver on Thursday promoting early-20th-century transit technology for revitalizing American cities this century.

Cities should "use streetcars as a tool for urban regeneration," said Shelley Poticha, head of Reconnecting America, a national group promoting high- density residential and commercial development in urban transit corridors.

Poticha and about 30 other local and national business, government and community officials joined in an all-day workshop at an East Colfax Avenue church on the reintroduction of streetcars to downtowns in cities including Portland, Ore.; Seattle; Kenosha, Wis.; Little Rock, Ark.; and Tampa, Fla.

Denver officials are considering returning streetcars to Colfax as a way to help revitalize one of the area's most important commercial corridors.

Six years ago, Portland opened the first 2.4 miles of its downtown streetcar system after spending about $57 million. It then added 1.6 more miles, said Vicky Diede of the city's transportation office.

That transit spending - largely done without federal support - has helped spawn as much as $3 billion in private commercial investment in the area, Diede told the workshop.

"We did three blocks in three weeks," she said, about the saw-cutting of streets, installation of tracks and repaving of the roadway.

"Before people could get irritated with us, we were gone," Diede said.

Keith Jones managed the bus system in Little Rock and was a self-confessed streetcar skeptic who became convinced of its value in helping bring his city's downtown back to life.

The city opened its 2.5-mile River Rail Streetcar line using "vintage" cars about three years ago, and it has helped spur about $350 million in residential and business development along the route, Jones told the group.

Jones now works for URS, a private firm that designs and builds transit lines.

Len Brandrup heads the transportation department for Kenosha and said small cities like his also can get a big return for a relatively small investment in the old steel-wheeled transit technology.

As a precursor to the possible introduction of streetcars on East Colfax, Denver and Aurora recently won a $3.18 million grant from the Colorado Department of Transportation to make transit upgrades to RTD's 15 Limited bus service from downtown Denver to Interstate 225 in Aurora.

The improvements include giving express buses traffic-signal priority and constructing "superstops" along the route, said Denver Public Works Department planner Jason Longsdorf.

Staff writer Jeffrey Leib can be reached at 303-954-1645 or jleib@denverpost.com.