Rancho Viejo is a census-designated place (CDP) in Starr County, Texas, United States.

It is a new CDP, formed from part of the La Rosita CDP prior to the 2010 census, with a population of 228.

[2] Rancho Viejo was first listed as a census designated place in the 2010 U.S. Census,[15] one of ten new CDPs (Anacua, Campo Verde, El Cenizo, Hilltop, La Chuparosa, Los Barreras, Los Ebanos, Miguel Barrera, Rancho Viejo, and Tierra Dorada) carved out of the La Rosita CDP.

[15] The CDP is within the Roma Independent School District.

[18] The zoned elementary school for the 2010 Census community is Delia Gonzalez (DG) Garcia Elementary School.