Texas Local Government Code - LOC GOV'T § 72.009. Suit to Establish Boundaries

(a) A county may bring suit against an adjacent county to establish the common boundary line. The suit must be brought in the district court of a county in an adjoining judicial district whose boundaries are not affected by the suit and whose county seat is closest to the county seat of the county that brings the suit. The court shall try the suit in the same manner in which it tries other suits.

(b) The district court has jurisdiction to determine where the boundary line is located and may order the line to be re-marked and resurveyed. The line established by the district court shall be treated as the true boundary between the counties unless the court determines that the line in question was established under prior law. If the district court determines that the boundary line has been established under prior law, the court shall declare that line to be the true boundary between the counties and shall have that line resurveyed and established as the boundary.

(c) The commissioner of the General Land Office may not mark a contested county line on the maps maintained by the land office until a certified copy of the final judgment is filed in the land office with a certified copy of the field notes of the boundary line established by the judgment.

(d) The remedy provided by this section is in addition to any other remedy prescribed by this chapter.