Whitman County, Washington

Whitman County is a county located in the U.S. state of Washington. As of the 2020 census, the population was 47,973. The county seat is Colfax, and its largest city is Pullman.

The county was formed from Stevens County in 1871. It is named after Marcus Whitman, a Presbyterian missionary who, with his wife Narcissa, was killed in 1847 by members of the Cayuse tribe.

Whitman County comprises the Pullman, Washington Metropolitan Statistical Area.

The area delineated by the future Washington state boundary began to be colonized at the start of the nineteenth century, both by Americans and Canadians. However, the majority of Canadian exploration and interest in the land was due to the fur trade, whereas American settlers were principally seeking land for agriculture and cattle raising. The Treaty of 1818 provided for dual control of this area by US and Canadian government officials. During this period, the future Washington Territory was divided into two administrative zones: Clark County and Lewis County (made official in 1845).

The dual-control concept was unwieldy and led to continual argument, and occasional conflict. The status of the Washington area was settled in 1846, when the Oregon Treaty ceded the land south of North latitude 49 degrees to American control.

In 1854, Skamania County was split from the original Clark County. Also in 1854, Walla Walla County was split from the new Skamania County. In 1863, Stevens County was split from Walla Walla County, and in 1871, a portion of Stevens County was set off to form Whitman County. The 1871 shape of Whitman County was considerably larger than its present boundary, as Adams, Franklin, and Lincoln counties were sectioned off from Whitman County in 1883. After that, Whitman County retained its shape, including through the period after Washington became the 42nd state of the Union in 1889.

According to the United States Census Bureau, the county has a total area of 2,178 square miles (5,640 km²), of which 2,159 square miles (5,590 km²) is land and 19 square miles (49 km²) (0.9%) is water. Whitman County is part of the Palouse, a wide and rolling prairie-like region of the middle Columbia basin.

As of the 2010 census, there were 44,776 people, 17,468 households, and 8,130 families living in the county. The population density was 20.7 people per square mile (8.0 people/km²). There were 19,323 housing units at an average density of 8.9 units per square mile (3.4 units/km²). The racial makeup of the county was 84.6% white, 7.8% Asian, 1.7% black or African American, 0.7% American Indian, 0.2% Pacific islander, 1.4% from other races, and 3.6% from two or more races. Those of Hispanic or Latino origin made up 4.6% of the population. In terms of ancestry, 29.4% were German, 14.5% were English, 13.4% were Irish, 7.1% were Norwegian, and 4.1% were American.