Florissant, MO has a population of 52,218 and is the 773rd largest city in the United States. The population density is 4,138 per sq mi which is 4690% higher than the Missouri average and 4467% higher than the national average. The median age in Florissant is 37 which is approximately 3% lower than the Missouri average of 38. In Florissant, 51% of the population over 15 years of age are married, 95% speak English and 2% speak Spanish. 76% of Florissant residents were born in Missouri, 20% were born out of state, 1% were born outside of the United States and 3% were foreign born.