Looking at the larger state scale, California is the most populous state in the United States with an estimated 36.8 million residents in 2008 (US Census Bureau 2008a). Its rate of population growth was explosive from after World War II to the first years of the 21st century. Although the rate of growth has slowed recently, it was still among the highest in the U.S. between 2000 and 2005 (Figure 3).
Figure 3. Percentage Rate of Population Growth, by State, 2000-2005
Source: US Census Bureau (2008)
This combination of a large population with a relatively high growth rate makes California an interesting location to consider the relationship between human population growth and competing land uses. In this case study, we will focus on southern California, specifically the greater Los Angeles metropolitan area. Based on its land area, Los Angeles is the biggest metropolitan area in the United States – comprised of an extensive grid of freeways, boulevards, and smaller neighborhood roads that span the City and County of Los Angeles and parts of four adjacent counties. The greater metropolitan area of Los Angeles (see map) has an estimated 17.9 million people, with 3.9 million people living in the city itself (Allianz Knowledge Partnersite 2008). According to the U.S. Census Bureau estimates (2008), this works out to 482 people per square mile in Los Angeles metro area. Compare this to the Census Bureau's estimated 217 people per square mile in the state of California overall and 80 people per square mile in the U.S. as a whole.
It should be noted that the administrative areas of these counties spread far beyond the urbanized area, so the density data are misleadingly low. The explosive population growth in this region growth, in the decades following World War II (Figure 4), led to great increases in the amount of land devoted to urban uses. As the population grew, land that was formerly used for agriculture in close proximity to Los Angeles became urbanized in Ventura, Orange, Riverside and San Bernardino counties. Although rates of population growth have slowed slightly in recent decades in Los Angeles County itself (Figure 4), more distant spaces are now becoming urbanized.
Figure 4. Population Growth in Greater Los Angeles Metropolitan Area since 1900
Data source: US Census Bureau.