Tempe, AZ has a population of 174,708 and is the 142nd largest city in the United States. The population density is 4,370 per sq mi which is 7502% higher than the Arizona average and 4724% higher than the national average. The median age in Tempe is 29 which is approximately 23% lower than the Arizona average of 37. In Tempe, 34% of the population over 15 years of age are married, 75% speak English and 14% speak Spanish. 37% of Tempe residents were born in Arizona, 48% were born out of state, 2% were born outside of the United States and 14% were foreign born.