Satellite images map the city's expansion across the Nevada desert from 1972 to 2010 in this video from NASA. Mark Byrnes at Atlantic Cities explains, "During that time, the Las Vegas metro area has seen its population grow from slightly under 300,000 to almost 2 million." For more numbers, check out Atlantic Cities' Las Vegas hub.
On the video page, NASA explains the color-coding of the images:
Las Vegas has undergone a massive growth spurt. This video shows the outward expansion of Las Vegas as a false-color time lapse of data from all 40 years of Landsat satellite data. The large red areas are actually green space, mostly golf courses and city parks. The images become a lot sharper around 1984, when new instrument designs improved the ability to resolve smaller parcels of land.
For more videos by NASA, visit http://www.nasa.gov/.