The Diocese of Brownsville was established on July 10, 1965, with the Most Rev. Adolph Marx, D.D., being installed as the first bishop of the diocese on September 2, 1965.
The Diocese of Brownsville is comprised of the counties of Cameron, Willacy, Hidalgo, and Starr. These counties are situated in the southernmost tip of Texas and border the Rio Grande River. The area of the four counties is 4, 226 square miles with a population of approximately 1,350,158 inhabitants. Of these approximately, 1,147,633 are Catholic.