I would suggest that, although the geological explanation is right, we should also consider that when LA was growing (1940-1960?) and when NY was growing (late half of the XIX century?) were different times with different technologies. Above all, the automobile played a major role in the shaping of LA and other american sprawls.

You might be surprised. The average height of a building in Los Angeles is 5.6 meters. While NYC's buildings have an average height of 8.4 meters, Chicago's average height is 4.8 meters and the buildings of notoriously sprawl-averse Portland average 4.7 meters.

By certain measures, LA is the densest metro area in the nation (thanks to its relative lack of low-density residential areas), ahead of NY and SF. While it's a giant city, its sprawl is limited by geographic factors - it's up against the ocean, and it's surrounded by high hills.

And keep in mind too that skyscrapers are not a cure-all for cities: They're much more expensive to build and maintain than shorter buildings (to say nothing of earthquake-proofing). This means skyscrapers attract rich tenants, concentrating wealth and aggravating inequality. It squelches innovation and drives out new businesses who can't afford to lease a skyscraper (but could afford an office in a midrise building).

Sources: http://www.citylab.com/design/2016/01/skyscrapers-cities-tall-buildings/431655/ http://www.citylab.com/commute/2015/02/a-new-index-to-measure-sprawl-gives-high-marks-to-los-angeles/385559/

I think the development of NYC and Los Angeles diverged due to the amount of space available for the cities to grow.

The vast majority of the skyscrapers in New York City are located in the borough of Manhattan, which is (for the most part) an island. Manhattan is roughly 23.7 square miles, including the parts not actually on Manhattan Island. There were also existing municipalities surrounding Manhattan, like Brooklyn and the Bronx, that restricted the potential for Manhattan to grow "out".

The City of Los Angeles, not counting the surrounding municipalities, is roughly 472 square miles. I can't find a citation at the moment, but much of the area surrounding the original pueblo of Los Angeles was farmland prior to the early-mid 1900s.

Los Angeles did not face the same geographical or political challenges to growing "out" as Manhattan did. A combination of this and the widespread adoption of cars around the time that Los Angeles started to grow into a large city led more outward development.

Unfortunately, I am not familiar enough with Chicago to comment on its development.

With all of this being said, I'd also like to point out that Los Angeles does have skyscrapers: image

It has to do with when the cities where settled, particularly in relation to the widespread use of private cars. Los Angles was developed much more recently. Currently, the LA metro area has a population of 18 million. In 1920, before many LA suburbs even existed, the city's population was around half a million. In contrast, the population of NYC only grew from 5 and half million to 8 million in the same time period.

LA was up during a time when urban planning was first starting to come together as a coherent profession, as opposed to just an architect or civil engineer. One of the first issues in this new idea of urban planning was a move away from the crowded, dirty industrial cities of the 19th century. Getting away from this style of living in large cities was made possible by the car, which allowed people to live miles and miles away from their work and still get there on time. Additionally, with the growing middle class, the idea of owning a single-family home actually became achievable, and LA became the poster city of the American dream.