Prehistoric cultural affiliation(s) include Adena, Hopewell and Late Adena dating back to 499 BC.
Many famous people are associated with these Washington County historic places including Rufus Putnam, Col. Josiah Harmar, Nahum Ward, Col. Joseph Barker, Gen. Rufus Putnam and Walter Curtis.
Some of the country's most noteable architects helped create the Washington County places including James & Sons Rees, Rolla Merydith, Hocking Valley Bridge Works, H. H. Townsend, Rufus Erastus Harte, Ebenezer B. Henderson, Smith Bridge Company, Ohio Company of Associates, Walker & Scott and U.S.Army Corps of Engineers. Prominent architectural styles found in Washington Country are Greek Revival, Federal and Gothic Revival.