Both historical and modern maps of Oregon are available on the Oregon Maps Collection page of this InfoGuide.
Historical topographic maps from the early 1900s to present can be viewed and downloaded using the National Map Download Client.
Find maps and nautical charts of Oregon’s coast, estuaries and larger, navigable rivers. Many charts date before 1900. From the Historical Map & Chart Collection search page:
Note: Search results can be filtered by source type (e.g., “nautical charts”) or year published by clicking on the column headings.
These maps, hand-drawn by surveyors hired by the United States General Land Office, were originally made to document the land claims made by settlers to this region. Though they can vary in detail, they are a rich cartographic resource showing the location of homesteads, roads, buildings and landforms. The majority of the maps date from 1852-1910.
The easiest way to access the maps is to use the map viewer provided by the BLM
You can also search the BLM's General Land Office Records.