Michael Manville and Donald Shoup [PDF]:
Without doubt, the cities of New York and San Francisco are denser than the city of LA. But sprawl is a regional attribute, and Los Angeles has much denser suburbs than New York or San Francisco. Indeed, the LA region's distinguishing characteristic may be the uniformity of its density; its suburbs have 82 percent of the density of its central city. In contrast, New York's suburban density is a mere 12 percent of its central city density, and San Francisco's suburban density is only 35 percent of the city's. New York and San Francisco look like Hong Kong surrounded by Phoenix, while Los Angeles looks like Los Angeles surrounded by . . . well, Los Angeles.
Los Angeles has (as evidently does Calgary) a reputation of being a "victim of urban sprawl", though the California city is in fact very dense, but just dense on a wide scale. Manville and Shoup then argue that Los Angeles' parking policies—that is, that the city requires a minimum amount of parking in a development—and the cost of land in a central business district (CBD) are an inhibiting factor in creating the vibrant street-life in the downtown core of the city. Unlike San Francisco or New York, the authors argue, there is little incentive to explore the shops and hangouts downtown because parking is so near to the event they just participated in or attended. They are careful to note that a sane parking policy will not lead to a vibrant CBD during the evening, but that an insane policy will prevent the existence of such vibrancy.