Relampago is a census-designated place (CDP) in Hidalgo County, Texas, United States.

The town was named for the Relampago Ranch, a rancho started in 1856 by José María Mora and Thaddeus Rhodes.

The town for some years has been a first stop on the so-called ferrocarril subterráneo for migrants.

16.7% of all households were made up of individuals, and 16.7% had someone living alone who was 65 years of age or older.

There were 18.5% of families and 38.3% of the population living below the poverty line, including 51.7% of under eighteens and 66.7% of those over 64.