Tranquillity, CA has a population of 724 and is the 17,257th largest city in the United States. The population density is 1,173 per sq mi which is 405% higher than the California average and 1194% higher than the national average. The median age in Tranquillity is 42 which is approximately 17% higher than the California average of 36. In Tranquillity, 51% of the population over 15 years of age are married, 37% speak English and 63% speak Spanish. 62% of Tranquillity residents were born in California, 7% were born out of state, 2% were born outside of the United States and 28% were foreign born.