Metro areas in the South and West grew the fastest from April 2010 to July 2011, according to new census data, but some cities, like Las Vegas, that saw major growth from 2000 to 2008 dropped significantly in the rankings.

Of the top 50 metropolitan areas with the highest growth, 46 were in the South or West with the number one area located in Kennewick-Pasco-Richland, Washington.

Robert Groves, director of the Census Bureau, said he attributes the numbers to how the nation is changing.

Areas like Las Vegas, which boasted third place for the fastest growing metro in the 2000 to 2010 decade, fell to 151st place in this recently released dataset.

“We’re already seeing different patterns of population growth than we saw in the last decade,” he said. The data indicates the American population tends to shift into areas of economic strength, thereby abandoning areas where the housing bubble grew largest.

Despite the recent changes, Texas still emerged as an exemplar for expansion, continuing its notable trend from the census numbers for the last decade of 2000 to 2010.

The collective Austin-Round Rock-San Marcos metropolitan statistical area held on to its title as one of the most rapidly flourishing spots in the country, ranking second for growth. With a 3.9% increase in this survey, its momentum continued from the previous decade, which showed growth of 37.3%.

Looking at numeric growth alone for 2010 to 2011, the Dallas-Fort Worth and Houston areas added more people than any other metro areas with an increase of roughly 155,000 and 140,000 people, respectively.

With this spike, Houston broke the 6 million mark.