Fern Prairie, WA has a population of 2,453 and is the 9,959th largest city in the United States. The population density is 489 per sq mi which is 406% higher than the Washington average and 440% higher than the national average. The median age in Fern Prairie is 41 which is approximately 9% higher than the Washington average of 38. In Fern Prairie, 60% of the population over 15 years of age are married, 94% speak English and 4% speak Spanish. 42% of Fern Prairie residents were born in Washington, 55% were born out of state, 1% were born outside of the United States and 2% were foreign born.