What's the $$ impact of a sports franchise? How 'bout zero?

At least that's the argument being put forth by the Seattle SuperSonics. Owners of the NBA franchise want to relocate the team to Oklahoma City. Stuck in a lease arrangement on a city-owned arena through 2010, owners are resorting to a unique form of economic warfare in order to get their way.

Of course, economists have long been skeptical of multi-million dollar impact studies by a sports franchise, almost always timed to the building of a new arena or a possible relocation.

As a University of Illinois researcher concluded a few years back, "professional sports generally have little, if any, positive effect on a city's economy."

What's unusual about the Sonics argument is that the sports team and the economists are on the same page.

Don't be surprised if a similar style argument makes it way to St. Louis some day. Consider the following:

The St. Louis Rams play their homes games inside a building design that's quickly becoming the dinosaur of the 21st century -- the permanently-domed stadium.

The Indianapolis Colts have played their last game inside the RCA dome. Pending legislative approval, the Minnesota Vikings are planning to abandon their current domed home in a few years. Both the Colts and Vikings new digs will feature a retractable roof.

That will leave St. Louis and just three other NFL teams -- Atlanta, Detroit and New Orleans -- as the only franchises in the sport that play all their home games in artificial conditions.

As recently as 1999, there were seven franchises with domed stadiums - the six above plus Seattle -- none with retractable roofs. If/when the Vikings move into their new home -- it will be a 4-4 split between the two designs. How much longer until the permanent dome disappears completely?

Of course, retractable roof stadiums don't come cheap. The one under discussion in Minnesota carries a $954 million pricetag. The cost for Lucas Oil Stadium, the new home of the Colts, is projected to be $675 million.

When the day of reckoning comes in St. Louis, who's going to pick up the tab? How much resistance will it meet? Will St. Louis County try to lure the Rams away from downtown? Will another city try to lure the Rams away from the region entirely? The possibilities and the arguments are endless.

It's one thing to build a new stadium in downtown Indianapolis, where the Colts are coming off last year's Super Bowl championship and have consistently been one of the NFL's top teams in the past decade. It's quite a different story in St. Louis where the franchise just finished a 3-13 campaign and is in transition following the death of Georgia Frontiere.

New owner Chip Rosenbloom has a lot of decisions to make.

A new stadium is no where close to the top of the list. But it's only a matter of time. Whether it's two years or ten years out, as the home of a football franchise, the Edward Jones Dome is an endangered species.

When that day happens, expect to hear a lot of arguments about the economic impact of the Rams on downtown St. Louis. Whether that number is a fortune or just fool's gold, taxpayers somewhere are going a pay a mint to find out.