Rio Hondo (Spanish for 'deep river') is located just east of the Brownsville-Harlingen-San Benito, Texas metro area off Farm roads 508 and 1846 on the northeastern boundary of Harlingen in north central Cameron County.
Rio Hondo was incorporated in 1939, when it had 713 residents and thirty-three businesses. The town population was an estimated 1,128 in 1950. In 1990 Rio Hondo reported a population of 1,793.
The Missouri Pacific line runs through the eastern side of town, and the Gulf Intracoastal Waterway cuts through the western part.