Marin City, CA has a population of 3,115 and is the 8,613th largest city in the United States. The population density is 5,803 per sq mi which is 2397% higher than the California average and 6306% higher than the national average. The median age in Marin City is 37 which is approximately 3% higher than the California average of 36. In Marin City, 50% of the population over 15 years of age are married, 63% speak English and 20% speak Spanish. 47% of Marin City residents were born in California, 26% were born out of state, 2% were born outside of the United States and 25% were foreign born.