Located in the Portland metropolitan area along Oregon Route 217, the shopping complex is one of the top grossing malls per square foot in the United States, with sales of $716/ft2.

[3] Opened in 1973, the mall is currently managed and co-owned by The Macerich Company, a real estate investment trust, and is anchored by Macy's, Nordstrom, JCPenney, Apple Store, and Dick's Sporting Goods.

[4] On May 3, 1972, plans for Oregon's largest shopping mall at that time were announced by Winmar Pacific, Inc.,[5] a developer bought by Safeco in 1967.

[10] Tigard was awarded the right to annex Washington Square along with other adjacent properties that contain Lincoln Center and the Embassy Suites Hotel.

In 2005, Macerich opened a 100,000 sq ft (9,300 m2) addition, housing 30 more stores (including The Cheesecake Factory, Sephora, Godiva Chocolatier, and Williams Sonoma).

[12] On October 15, 2018, original anchor store Sears announced that their location at Washington Square would be closing as part of the chain's bankruptcy filing.