AreaVibes reveals the best places to live in Washington for 2016 using our Livability Score. The Livability Score for each city in Washington is calculated out of 100 from a unique algorithm based on various metrics, including: amenities, cost of living, crime, education, employment, housing and weather. Washington has a population of 6,899,123 and a population density of 96.7 people per square mile. The capital city is Olympia and the largest city in Washington is Seattle. To filter the results, use the dropdown options to sort by population or category.