(a) This subchapter applies only to a district located wholly in:
(1) a county with a population of 20,000 or less; or
(2) a county with a population of more than 30,000 but less than 41,000 that is adjacent to a county with a population of more than 200,000 but less than 233,500.
(b) The board of a district described by Subsection (a) may create a new district by disannexing territory from the existing district and ordering a new district to be created in the disannexed territory in the manner provided by this subchapter.