The problems with parking minimums are both numerous and obvious. First and foremost, the convenience of off-street parking spaces promotes driving, even in cities with efficient and expansive transit systems. The more spaces developers must build, the less space they have for actual residential units, which raises rents; meanwhile, mandatory parking spaces can displace ground-level retailers. And last, if you're not into the whole sustainability or economics thing, off-street parking facilities just aren't very attractive.
Still it's often assumed that without parking minimum regulations in place developers would still build a great deal of parking spaces - perhaps even more than is required of them - to meet demand. But that might not be the case, according to a new report by the N.Y.U. Furman Center [PDF]. After a thorough review of minimum parking regulations and off-street spaces in New York City, the study authors concluded that "more parking spaces exist today than would have been built without the requirements":