Question: where does the rio grande start and finish
Answer: 53833 Mouth Gulf of Mexico - location Cameron County , Texas ; Matamoros , Tamaulipas - elevation 0 ft ( 0 m ) - coordinates 25 ° 57 ′ 22 '' N 97 ° 8 ′ 43 '' W ﻿ / ﻿ 25.