The other way around really. Houston's size comes primarily from the city itself, not the outlying areas. Houston is the 4th largest city in the United States, and the largest city in Texas. However, what most people don't know is that the Houston GMA is smaller than the Dallas/Fort Worth GMA. 7 of the 10 largest cities in Texas are part of the DFW metroplex.
Posters 265 and 266 got it. What can I say?