Records include correspondence, memoranda, reports, specifications and standards, permits, deeds, drawings, and other materials related to public works, capital improvements, and public utilities, as well as routine affairs of the Seattle Engineering Department. A majority of the documents have been reformatted to microfiche, but 38 boxes (15.2 cubic feet) of original paper documents are also included in the collection. Important subjects relating to public works and engineering functions include traffic planning and control, transportation, garbage and solid waste management, sewers, street maintenance and design, and water supply. Other topics include: bicycles, bridges, carpools, pollution, and landslides. Principal internal operations are also covered substantially, such as budgeting, contract agreements, permit control, and status reporting for both internal and external audiences. An important subset of these documents is correspondence received from the public, such as petitions, permits, complaints, and claims, as well as the departmental response.

Significant inter-departmental and inter-jurisdictional communication between the Engineering Department and the Washington State Department of Transportation, the Seattle Housing Authority, the Department of Parks and Recreation, the Department of Community Development, and the Mayor's Office, are present in substantial amounts, as well as with the Municipality of Metropolitan Seattle (Metro). Notable engineering projects covered included the Alaskan Way Viaduct, the Monorail, public transit, the Forward Thrust Initiative Series, and the 1962 Century 21 Exposition. The Unrecorded Subject Files comprises the Seattle Engineering Department's central filing system up to 1988. Almost all records were microfilmed by the Department's Administrative Records Center until its dissolution in the late 1980s. Records date from 1890 to 1990. Early correspondence includes topics such as paving materials; 1917 correspondence with the Minneapolis Engineer regarding their use of wood blocks as experimental paving material is an example. Records are arranged alphabetically.