Arlington is located in Middlesex county Massachusetts with a geographic area of 5.1 square miles. The total population in Arlington is 45,379 with 46.8% male and 53.2% female. Children under age 5 represent 6.5% of the population, under age 18 equal 21.3% of the population and over age 65 is 16.1% of the population. The median household income is $114,576, per capita income is $63,578. There are a total of 19,118 housing units with 57.9% owner occupied. Education includes 11.2% of residents that are high school graduates and 74.5% with a bachelor's degree or higher. The average temperature in Arlington in the summer is 70 degrees, and in the winter 30 degrees.