Most major cities have had "parking minimums" on the books since the 1950s: Whenever a new development goes up—be it a home, store, office—there have to be a minimum number of parking spots built, as well. The logic is that this prevents spillover onto the neighborhood streets. But the AP had a good story last week about how many cities, including Washington, D.C., are now rethinking these requirements:

In practice, critics say, the requirements create an excess supply of parking, making it artificially cheap. That, the argument goes, encourages unnecessary driving and makes congestion worse. The standards also encourage people to build unsightly surface lots and garages instead of inviting storefronts and residential facades, they say. Walkers must dodge cars pulling in and out of driveways, and curb cuts eat up space that could otherwise be used for trees. ...

Opponents also say the standards force developers to devote valuable land to parking, making housing more expensive.

That's about right. Supporters of the minimums argues that every new building needs lots and lots of parking, or else the people moving in will just park on the street, taking spaces away from existing residents. But, in practice, particularly in denser, transit-oriented areas, the supply of cars isn't fixed at all—if the cost of parking rises, then some people will decide to forgo cars, or take the subway or bus. Many of D.C.'s historic neighborhoods—Dupont, Georgetown—sprung up before parking minimums, and, as a result, are a great deal more walkable. Conversely, when zoning regulations artificially lower the price of driving, there's more of it. (It's also noteworthy that, as Donald Shoup notes, very few minimum-parking laws were based on any sort of empirical reseach.)

More to the point, though, if the problem that needs to be addressed is a lack of street parking in a neighborhood, then, as Dave Alpert argues, a better answer is often more effective on-street management—placing tighter limits on who can park in the area, or charging non-residents for parking. (Most D.C. neighborhoods have two-hour limits for non-residents on weekdays, but employees in the area often just move their cars every two hours, and parking still gets clogged on nights and weekends—so that policy could use reworking.) This can require some experimenting around—and, yes, in some cases, you really do need to build more parking—but there are fewer drawbacks to pricing parking correctly than there are to mandatory minimums that distort development patterns.

--Bradford Plumer