Plains, TX has a population of 1,377 and is the 13,191st largest city in the United States. The population density is 1,399 per sq mi which is 1344% higher than the Texas average and 1445% higher than the national average. The median age in Plains is 38 which is approximately 12% higher than the Texas average of 34. In Plains, 64% of the population over 15 years of age are married, 56% speak English and 43% speak Spanish. 63% of Plains residents were born in Texas, 18% were born out of state, 0% were born outside of the United States and 19% were foreign born.