Several studies have found that cruising for curb parking generates about 30 percent of the traffic in central business districts. In a recent survey conducted by Bruce Schaller in the SoHo district in Manhattan, 28 percent of drivers interviewed while they were stopped at traffic lights said they were searching for curb parking. A similar study conducted by Transportation Alternatives in the Park Slope neighborhood in Brooklyn found that 45 percent of drivers were cruising.
…What causes this astonishing waste? As is often the case, the prices are wrong. A national study of downtown parking found that the average price of curb parking is only 20 percent that of parking in a garage, giving drivers a strong incentive to cruise.
Here is more, from Donald Shoup.