Robertsville, NJ has a population of 11,930 and is the 3,433rd largest city in the United States. The population density is 2,021 per sq mi which is 202041% higher than the New Jersey average and 2131% higher than the national average. The median age in Robertsville is 42 which is approximately 7% higher than the New Jersey average of 40. In Robertsville, 66% of the population over 15 years of age are married, 78% speak English and 3% speak Spanish. 39% of Robertsville residents were born in New Jersey, 43% were born out of state, 1% were born outside of the United States and 17% were foreign born.