Morris Plains, NJ has a population of 5,612 and is the 6,002nd largest city in the United States. The population density is 2,198 per sq mi which is 219731% higher than the New Jersey average and 2326% higher than the national average. The median age in Morris Plains is 43 which is approximately 9% higher than the New Jersey average of 40. In Morris Plains, 66% of the population over 15 years of age are married, 89% speak English and 6% speak Spanish. 63% of Morris Plains residents were born in New Jersey, 26% were born out of state, 1% were born outside of the United States and 9% were foreign born.