County · code 41051
Multnomah CountyOregon
Multnomah County is in Oregon and has its county seat in Portland. The county was established on December 22, 1854, from parts of Clackamas and Washington counties.
- Founded1854
- County seatPortland
- Named forMultnomah people
- Land area431 sq mi + 34 sq mi water
- Population815,428 2020 Census
- Parcels mapped284,358 checked 15 October 2026
Where it is
Multnomah on the map of Oregon
Oregon has 36 counties and county equivalents, each with its own records office. Shapes with a page are links.
History
Formed in 1854 from Clackamas County and Washington County
An old deed may name a county that no longer exists, or a boundary that has since moved.
Multnomah County was created by Oregon Territory from Clackamas and Washington counties on December 22, 1854. The county was named after the Multnomah people. When Oregon became a state in 1859, Multnomah became an official Oregon county as Oregon Territory was eliminated.
- 1854Multnomah County created Multnomah created by Oregon Territory from Clackamas and Washington. · Ore. Terr. Special Laws 1854, 6th reg. sess., p. 29
- 1859Became part of Oregon Multnomah became an Oregon county when the state of Oregon was admitted to the Union and Oregon Territory was eliminated. · U.S. Stat., vol. 11, ch. 33[1859], secs. 1-2/pp. 383-384 Ore. Laws 1860, 1st reg. sess., pp. 28-30
- 1864Gained territory Multnomah gained from Columbia. · Ore. Laws 1864, 3rd reg. sess., p. 62
- 1885Gained territory Multnomah gained from Columbia. · Ore. Special Laws 1885, 13th reg. sess., p. 324
- 1901Exchanged territory Multnomah exchanged with Columbia. · Ore. Laws 1901, 21st reg. sess., pp. 126-127
Show all 10 changes
- 1854Multnomah County created Multnomah created by Oregon Territory from Clackamas and Washington. · Ore. Terr. Special Laws 1854, 6th reg. sess., p. 29
- 1857Lost territory Multnomah lost very small area near the head of Eagle Creek and Bradford's Island to Wasco. · Ore. Terr. Laws 1856-1857, 8th reg. sess., pp. 78-79
- 1859Became part of Oregon Multnomah became an Oregon county when the state of Oregon was admitted to the Union and Oregon Territory was eliminated. · U.S. Stat., vol. 11, ch. 33[1859], secs. 1-2/pp. 383-384 Ore. Laws 1860, 1st reg. sess., pp. 28-30
- 1864Gained territory Multnomah gained from Columbia. · Ore. Laws 1864, 3rd reg. sess., p. 62
- 1885Gained territory Multnomah gained from Columbia. · Ore. Special Laws 1885, 13th reg. sess., p. 324
- 1893Gained territory Multnomah gained small area (part of the town of Sellwood) from Clackamas. · Ore. Laws 1893, gen., 17th reg. sess., pp. 78-79
- 1895Changed Multnomah boundary with Wasco adjusted within Section 22 of Township 2 North, Range 7 East. · Ore. Laws 1895, 18th reg. sess., p. 88
- 1901Exchanged territory Multnomah exchanged with Columbia. · Ore. Laws 1901, 21st reg. sess., pp. 126-127
- 1931Lost territory Multnomah lost to Columbia. · Ore. Laws 1931, gen., 36th reg. sess., ch. 289/p. 515
- 1967Boundary clarified Multnomah redefined to substitute "boundary of the state" for middle of the main channel of the Columbia River. Approved by the Governor 19 June 1967, became effective 13 Sep 1967 (no change).no change· Ore. Laws 1967, 54th reg. sess., ch. 421/p. 928
Land and parcels
What the maps cover in Multnomah
Who publishes each layer, how good it is, and when we last checked.
-
Parcels Good enough
Lot lines and tax-map numbers for 284,358 parcels. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
checked 15 October 2026 -
Address points Official
One point per address, 276,533 in all from State of Oregon — Department of Administrative Services Geospatial Enterprise Office (GEOHub) with Oregon Department of Emergency Management 9-1-1 program.
edited 16 January 2026 · checked 13 October 2026 -
Buildings Reference
Roof outlines traced from aerial imagery from FEMA Response Geospatial Office with Oak Ridge National Laboratory (ORNL). Good for seeing what is on a lot; not accurate enough to set a fence from.
checked 18 October 2026
- Official
- from the office that keeps the record
- Good enough
- a reliable statewide or national copy
- Fallback
- a guide only; check the official record
- Missing
- nothing public found yet
People and land
Multnomah by the Census
Source: US Census Bureau, 2020 Census; US Census Bureau, 2020 Gazetteer Files. Not endorsed or certified by the Census Bureau.
Rules and offices
Multnomah County's official site
We have found the county's site but not its offices yet; start there.
County government
- County government
The official website of Multnomah County.
See your own lot on these maps
Open Multnomah County on Parcel Chart's free map and click your parcel. Save it with a free account; the full record of your place (site map, projects, documents) is Pro, in early access.
Questions
Common questions about Multnomah County
- When was Multnomah County founded?
- Multnomah County was founded in 1854, formed from Clackamas County and Washington County, and named after Multnomah people.
- What is the county seat of Multnomah County?
- The county seat of Multnomah County is Portland.
- Is there an online parcel map for Multnomah County?
- Yes. A public source publishes a parcel map of 284,358 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
- Has Multnomah County's boundary or name changed?
- Multnomah County was created in 1854 from Clackamas County and Washington County. Since then the Atlas of Historical County Boundaries records 8 later changes, chiefly involving Columbia County, Wasco County and Clackamas County.
- Is my lot in a flood zone?
- We do not have flood maps for Multnomah County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.
Nearby