On a percentage basis, Las Vegas and Clark County experienced incredibly high growth rates starting in the 1930s and lasting until the late 2000s recession. During that period, the population of the city more than doubled in most decades. The rate slowed down in the 1970s with the decrease of the white birth rate, but never dropped below 60% (1980–1990), and even accelerated after 1990 due to immigration. By 2000, Las Vegas was the largest city founded in the 20th century, and by 2006 it was the 28th largest city in the US, with a population of 552,000 in the city and nearly 1.8 million in Clark County. The explosive growth resulted in rapid development of commercial and residential areas throughout the Las Vegas Valley. The strong boom in the resort business led to many new condominium developments all along the Strip and downtown area. Also urban sprawl development of single-family homes continued across the valley, building the areas of Henderson, North Las Vegas, Centennial Hills, and Summerlin. The rapid development and population growth both halted abruptly in the late 2000s recession.