Back in the 70s, Poughkeepsie closed off a few blocks of its Main Street permanently to traffic in order to make it into a pedestrian mall, the "Main Mall". This made a big mess of downtown traffic, especially considering that some other streets were being dug up at the time to construct an "east-west arterial" that wouldn't be finished for a few more years, so there really wasn't a good way to go east or west across town. But that was supposed to be the price of progress, as this move was necessary to allow the downtown stores to compete with suburban malls.
The Main Mall was opened with great fanfare right around the time of the Bicentennial, and promptly found that as soon as the bands, balloons, and free giveaways of the grand opening ceremony went away, so did most of the shoppers, and the stores did less business than they had when the street was open to traffic. Soon the stores started going out of business or moving to the suburbs, which reduced the crowds still further, as there was less reason to go there.
The county took over a vacant department store (Luckey Platt, which had been a local fixture for many decades, and used to have signs all over the region saying how many miles it was to their store; they were considered the major anchor of the Main Mall, but went under shortly after its opening) and put their Social Services office there, which made middle class people even more unwilling to go near there because "it's full of drunks, druggies, and other bums." There was even talk of removing all the benches so that vagrants wouldn't loiter, though that would make the place less comfortable to "normal" people too. Ultimately, after years of failure, they converted part of it back to a real street, but left part as a pedestrian mall even though it's a ghost town that seldom sees any actual pedestrian traffic and has very few things on it that anybody would want to go to.
Update: I just drove past there (in 2001), and the whole "mall" portion of the street has been dug up, so apparently they're in the process of turning it back into a regular street now. (As of 2003 I'm not sure of its current status.)