Hamilton is an unincorporated

Unincorporated area

In law, an unincorporated area is a region of land that is not a part of any municipality.To "incorporate" in this context means to form a municipal corporation, a city, town, or village with its own government. An unincorporated community is usually not subject to or taxed by a municipal government...

 community in Grant County

Grant County, Oregon

Grant County is a county located in the U.S. state of Oregon. It is included in the 8 county definition of Eastern Oregon. In 2010, its population was 7,445. It is named for President Ulysses S. Grant, who served as an army officer in the Oregon Territory, and at the time of the county's creation...

, Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

, United States. It is located on Oregon Route 402

Oregon Route 402

Oregon Route 402 is an Oregon state highway running from Kimberly to Long Creek. OR 402 is known as the Kimberly-Long Creek Highway No. 402...

 east of Monument

Monument, Oregon

Monument is a city in Grant County, Oregon, United States. The population was 151 at the 2000 census. It is located near the confluence of the North Fork and Middle Fork of the John Day River.-Geography:...

 and west of Long Creek

Long Creek, Oregon

Long Creek is a city in Grant County, Oregon, United States. The population was 228 at the 2000 census. The city is named after John Long, a prominent miner who came to Grant County in 1862 during the Canyon City rush of that same year. Located in a high valley of the Blue Mountains, ranching has...

. As of 1993, the community had no businesses and only three houses.

The community and nearby Hamilton Mountain were named for John Henry Hamilton, the first settler in the area. Hamilton, a cattle rancher, arrived in Grant County sometime in 1874 and lived there until his death in 1909. Local settlers met at Hamilton's ranch to race horses. Hamilton post office was established in 1884 and closed in 1959. Anson C. Frink built the first store and served as the first postmaster.