San Diego, TX has a population of 4,563 and is the 6,872nd largest city in the United States. The population density is 2,400 per sq mi which is 2376% higher than the Texas average and 2549% higher than the national average. The median age in San Diego is 33 which is approximately 4% lower than the Texas average of 34. In San Diego, 48% of the population over 15 years of age are married, 35% speak English and 65% speak Spanish. 93% of San Diego residents were born in Texas, 3% were born out of state, 1% were born outside of the United States and 3% were foreign born.