Mars, PA has a population of 1,415 and is the 13,041st largest city in the United States. The population density is 3,006 per sq mi which is 985% higher than the Pennsylvania average and 3218% higher than the national average. The median age in Mars is 42 which is approximately 4% higher than the Pennsylvania average of 41. In Mars, 61% of the population over 15 years of age are married, 98% speak English and 1% speak Spanish. 81% of Mars residents were born in Pennsylvania, 17% were born out of state, 1% were born outside of the United States and 1% were foreign born.