La Prairie, IL has a population of 68 and is the 27,706th largest city in the United States. The population density is 291 per sq mi which is 31% higher than the Illinois average and 221% higher than the national average. The median age in La Prairie is 46 which is approximately 23% higher than the Illinois average of 37. In La Prairie, 68% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 75% of La Prairie residents were born in Illinois, 22% were born out of state, 0% were born outside of the United States and 3% were foreign born.