Will Houston overtake Chicago as the nations third largest city?

I think the obvious answer is yes, but how soon (or if) that happens will depend on a number of factors. The numbers you site for population are close and, without researching them, I believe fairly accurate. However, the numbers that I think are more indicative of the difference in the two cities is the population in the Metropolitan Area for each city. Chicago/Naperville/Joliet metro area is 9.5 million where Houston/Sugar Land/Baytown is 5.5 million. The difference here is much larger. Certainly Houston's growth rate is quite high, growing 25.2% between '90 and 2000. Chicago grew 11.6 % in the same time period. If these 2000 rates were right and sustained, then Chicago proper is already smaller (and event that would have occurred in 2003). The metro areas tell the same story only later. Houston metro would have surped Chicago metro last year. We'll have to see on the next census in 2010 to see if the trends held up.