[3] It is named after Marcus Whitman, a Presbyterian missionary who, with his wife Narcissa, was killed in 1847 by members of the Cayuse tribe.

[4] 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.

The Treaty of 1818 provided for dual control of this area by US and Canadian government officials.

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.

After that, Whitman County retained its shape, including through the period after Washington became the 42nd state of the Union in 1889.

[5] Whitman County is part of the Palouse, a wide and rolling prairie-like region of the middle Columbia basin.

21.9% were of German, 9.8% English, 8.6% Irish, 8.3% United States or American and 6.6% Norwegian ancestry.

It is part of Washington's 5th congressional district and is represented by Republican Michael Baumgartner.

Quite conservative, rural Whitman was one of only three counties in the state to be won by Barry Goldwater in 1964.

Richard Nixon, Ronald Reagan, Bill Clinton, and George W. Bush each won the county twice.

[16] Whitman was the only county in eastern Washington to approve same-sex marriage via Referendum 74.

However, Republican Bill Bryant won this county over incumbent Democrat Jay Inslee by a percentage point in the concurrent gubernatorial election.

In the 2020 elections, the majority of the county voted for Democrat Joe Biden for president and re-elected Inslee for governor.