Supervisor Chris Daly wants to close Market Street to all but mass transit traffic.

As I wrote in May, that idea has failed in city after city. In Chicago, State Street — “that great street” — utterly died when they tried it there. They re-opened the street to all traffic a few years ago, and the street is recovering.

Market Street isn’t some quaint pedestrian mall like Boulder’s Pearl Street, and it never will be. It’s a living artery in a major city. Daly’s plan would be an economic and social disaster.