San Juan is a city in Hidalgo County, Texas, United States. As of the 2020 census the population was 35,294, an increase over the figure of 33,856 tabulated in 2010. It is part of the McAllen–Edinburg–Mission and Reynosa–McAllen metropolitan areas. The city is known for the Basilica of the National Shrine of Our Lady of San Juan del Valle, one of the largest churches in South Texas.