The Map Collection contains over 25,000 maps that focus on Western exploration and the Oregon Territory. Available types of maps include those of the Oregon Territory, the state, cities and counties, and special subjects such as mining, forestry, railroads, coasts and rivers, soils, farmlands, land claims, Native Americans and explorations.

A special feature of the collection is the collection of Sanborn Fire Insurance Maps (see the Sanborn Fire Insurance maps of Portland-1 and the Sanborn Fire Insurance Maps of Portland-2) which present detailed information on the city in approximate 10-year intervals from 1879 to 1965.