Tex. Local Government Code § 71.021: ATTACHMENT OF COUNTIES.

(a) Until a new county is legally organized, the territory of the new county remains subject to the county from which it is taken.

(b) A legally organized county that, for any reason, loses its county organization is attached to the organized county whose county seat is closest to that of the disorganized county. The attachment is made for judicial and surveying purposes and for the registration of a deed, mortgage, or other instrument that is required or permitted by law to be recorded. The disorganized county remains attached until it is again legally organized.

Acts 1987, 70th Leg., ch. 149, Sec. 1, eff. Sept. 1, 1987.