Liberty, MO has a population of 30,239 and is the 1,410th largest city in the United States. The population density is 1,049 per sq mi which is 1114% higher than the Missouri average and 1058% higher than the national average. The median age in Liberty is 37 which is approximately 3% lower than the Missouri average of 38. In Liberty, 57% of the population over 15 years of age are married, 96% speak English and 2% speak Spanish. 60% of Liberty residents were born in Missouri, 37% were born out of state, 1% were born outside of the United States and 2% were foreign born.