All of the "Katy area" lies in the city of Houston's extraterritorial jurisdiction (ETJ), not Katy's ETJ. This means that the areas of "Katy area" are controlled by the city of Houston and the city has the ability to annex it in the future. The city of Katy cannot annex this area unless the city of Houston releases the area's ETJ to Katy, which has occurred in several small chunks in recent years. The most recent instance of this was in 2001 when Houston ceded about 400 acres (1.6 km²) of ETJ to the City of Katy to allow the Katy Mills Mall and surrounding parking lot to be built entirely within the City of Katy.
The "Katy area" contains well over 250,000 people.