Pine Grove, WA has a population of 141 and is the 25,875th largest city in the United States. The population density is 288 per sq mi which is 198% higher than the Washington average and 218% higher than the national average. The median age in Pine Grove is 63 which is approximately 68% higher than the Washington average of 38. In Pine Grove, 86% of the population over 15 years of age are married, 89% speak English and 11% speak Spanish. 85% of Pine Grove residents were born in Washington, 15% were born out of state, 0% were born outside of the United States and 0% were foreign born.