Generally, when a city annexes an area, the ETJ “expands with the annexation to comprise, consistent with Section 42.021, the area around the new municipal boundaries.” Id. § 42.022(a); but see, e.g., id. § 42.0225. For example, when a city of 100,000 or more inhabitants annexes an area, its new ETJ would generally comprise the unincorporated area contiguous to the new city boundaries within five miles of the new boundaries. See id. § 42.021(5).
It should be noted that the ETJ of a city may not expand — whether it be by an increase in the number of inhabitants, on request of a landowner, or through annexation — into another city’s ETJ without that city’s consent. Id. §§ 42.022(c), 42.023. And the ETJ of a city generally may not be reduced, unless the city council of the city gives its written consent. Id. §§ 42.022(d), 42.023.