When was Gilliam County founded?

Gilliam County was founded in 1885, formed from Umatilla County and Wasco County, and named after Cornelius Gilliam.

What is the county seat of Gilliam County?

The county seat of Gilliam County is Condon.

Is there an online parcel map for Gilliam County?

Yes. Gilliam County publishes a parcel map of 3,171 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.

Has Gilliam County's boundary or name changed?

Gilliam County was created in 1885 from Umatilla County and Wasco County. Since then the Atlas of Historical County Boundaries records 2 later changes, most of them small boundary adjustments, chiefly involving Crook County, Wasco County and Wheeler County.

Is my lot in a flood zone?

We do not have flood maps for Gilliam County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

County · code 41021

Gilliam CountyOregon

Gilliam County is a county in Oregon, with its seat in Condon. It was formed on February 25, 1885 from parts of Umatilla and Wasco counties.

Founded1885
County seatCondon
Named forCornelius Gilliam
Land area1,205 sq mi + 18 sq mi water
Population1,995 2020 Census
Parcels mapped3,171 checked 14 October 2026

Open the free map Click any parcel in Gilliam County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated 19 October 2026

Census outline · seat marked

History

Formed in 1885 from Umatilla County and Wasco County

An old deed may name a county that no longer exists, or a boundary that has since moved.

Gilliam County was named after Cornelius Gilliam. When Gilliam was created from Umatilla and Wasco in 1885, a small strip of Wasco was inadvertently left on Gilliam's southeastern line, which Gilliam gained back in 1891. In 1899, Gilliam lost territory to the creation of Wheeler County and lost a small area along the John Day River to Crook County.

Boundary changes from the Newberry Library, Atlas of Historical County Boundaries.

1885
Gilliam County created Gilliam created from Umatilla and Wasco. Creation left a small strip of Wasco along the southeastern line of Gilliam which remained until gained by Gilliam on 20 February 1891.
from Umatilla from Wasco
25 February 1885 · Ore. Special Laws 1885, 13th reg. sess., p. 404
1891
Gained territory Gilliam gained from Wasco. The gain was a small strip that was inadvertently separated from Wasco when Gilliam was created on 25 February 1885.
from Wasco
20 February 1891 · Ore. Laws 1891, gen., 16th reg. sess., p. 76
1899
Lost territory Gilliam lost to creation of Wheeler and lost a small area along the John Day River to Crook.
to Wheeler to Crook
17 February 1899 · Ore. Laws 1899, 20th reg. sess., pp. 51-55
1927
Boundary clarified Gilliam redefined (no change).
no change
9 February 1927 · Ore. Laws 1927, gen., 34th reg. sess., ch. 52/p. 60
1967
Boundary clarified Gilliam 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
13 September 1967 · Ore. Laws 1967, 54th reg. sess., ch. 421/p. 926

Land and parcels

What the maps cover in Gilliam

Who publishes each layer, how good it is, and when we last checked.

Parcels Good enough

Lot lines and tax-map numbers for 3,171 parcels from Gilliam County. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
edited 12 August 2026 · checked 14 October 2026
Address points Official

One point per address, 1,450 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

Gilliam by the Census

Population

1,995 2020 Census count

Housing units

1,095 2020 Census count

Land area

1,205 square miles

Water area

18 square miles

People per sq mi

2 population ÷ land area

Source: US Census Bureau, 2020 Census; US Census Bureau, 2020 Gazetteer Files. Not endorsed or certified by the Census Bureau.

Rules and offices

Gilliam 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 Gilliam County.
co.gilliam.or.us

See your own lot on these maps

Open Gilliam 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.

Open the free map no sign-in Pro early access

Questions

Common questions about Gilliam County

When was Gilliam County founded?: Gilliam County was founded in 1885, formed from Umatilla County and Wasco County, and named after Cornelius Gilliam.
What is the county seat of Gilliam County?: The county seat of Gilliam County is Condon.
Is there an online parcel map for Gilliam County?: Yes. Gilliam County publishes a parcel map of 3,171 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Gilliam County's boundary or name changed?: Gilliam County was created in 1885 from Umatilla County and Wasco County. Since then the Atlas of Historical County Boundaries records 2 later changes, most of them small boundary adjustments, chiefly involving Crook County, Wasco County and Wheeler County.
Is my lot in a flood zone?: We do not have flood maps for Gilliam County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby