Austin, TX has a population of 864,218 and is the 11th largest city in the United States. The population density is 2,786 per sq mi which is 2793% higher than the Texas average and 2975% higher than the national average. The median age in Austin is 32 which is approximately 6% lower than the Texas average of 34. In Austin, 44% of the population over 15 years of age are married, 67% speak English and 25% speak Spanish. 53% of Austin residents were born in Texas, 27% were born out of state, 2% were born outside of the United States and 18% were foreign born.