General Motors' decision to move its factories from Flint (workers earn US minimum wage) to Mexico (workers earn 70 cents an hour) makes perfect economic sense - right? Wrong.

As soon as you factor in the very real social cost of taking tens of thousands of workers and putting them on the dole, it becomes clear that only a madman (or maybe a very, VERY rich CEO of a major corporation) would do it.

This is the message that comes from Michael Moore's bitingly funny documentary on the collapse of an American town.

On one level, Moore's movie simply shows his good-natured fight to interview General Motors CEO Roger Smith and bring him to Flint to see the devastation for himself.

But at the heart of this movie, we see Flint's descent into a living hell where half the population are on welfare.

Many former GM car workers are inmates in the shiny new prison there - while many others are their guards.

An attempt to attract tourists by building the Auto World theme park, a Hyatt Regency Hotel and a new shopping mall hits the rocks within months, the buildings adding a new layer of plaque to the broken heart of Flint.

While this film has scenes that some viewers may find upsetting, the story is not a downbeat one.

The real tragedy is that 1950s Flint was an all-American town that looked like it inspired Norman Rockwell paintings.

But in just a few short years, corporate greed reduced it to a grubby, hinterland - hell, they may as well have just bombed it...

When it came out, this movie set a new box office record for a documentary.

What knocked it off the top slot in 2002? Michael Moore's exploration of America's obsession with guns - Bowling for Columbine.

Mike Taylor