Whitman County is a county located in the U.S. state of Washington. As of the 2010 census, the population was 44,776, with the majority living in its largest city, Pullman, home to Washington State University, the state's land-grant university. The county seat is at Colfax.
Whitman County was formed out of Stevens County on November 29, 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.