The area delineated by the future Washington state boundary was 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 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 latitude 49 degrees North to American control.

In 1862, Bob Bracken became the first permanent European settler of what would become Asotin county.

It is part of the Palouse, a wide and rolling prairie-like region of the middle Columbia basin.

[12] In terms of ancestry, 32.4% were German, 14.8% were Irish, 13.7% were English, 7.5% were American, and 6.2% were Norwegian.

25.9% were of German, 12.4% English, 11.9% Irish and 11.0% United States or American ancestry.

27.00% of all households were made up of individuals, and 11.70% had someone living alone who was 65 years of age or older.

Generally, Asotin County is considered a staunchly Republican area, although it has been known to vote for Democrats, especially on the state level.

In the 2004 Presidential election slightly over 60 percent of the vote went to Republican George W. Bush.

It was one of 11 of Washington's 39 counties where Bush received a lower percentage of the vote in 2004 than in 2000.