Map for Washington County Administration Map for Washington County Administration Search | Advanced Search | New Members | Coupons and Discounts | All Categories Government & Education >> GOVERNMENT AGENCIES Washington County Administration 155 N 1st Ave, #300, MS-21Hillsboro, OR 97124 | directions (503) 846-8685 | fax: (503) 846-4545 Visit Site If your business isn't here, contact us today to get listed!