Arlington is located in Snohomish county Washington with a geographic area of 9.8 square miles. The total population in Arlington is 19,947 with 48.2% male and 51.8% female. Children under age 5 represent 5.6% of the population, under age 18 equal 22.9% of the population and over age 65 is 13.9% of the population. The median household income is $77,023, per capita income is $36,540. There are a total of 7,820 housing units with 65.9% owner occupied. Education includes 26.6% of residents that are high school graduates and 21.8% with a bachelor's degree or higher. The average temperature in Arlington in the summer is 60 degrees, and in the winter 42 degrees.