He is remembered primarily for his role in three milestones of the old American West: the founding of the University of Washington, the Mercer Girls, and the Johnson County War.

[2] In 1861, as a member of one of the founding families of Seattle, Washington, a young Asa Mercer assisted his brothers in clearing stumps to make way for the new territorial university.

[3] The young town of Seattle was attracting hordes of men to work in the timber and fishing industries, but few marriageable women were willing to make the trip to the remote northwest corner of the United States.

In March 1864, with public support and private funding, Mercer traveled to the eastern United States in search of single women to work in Seattle as teachers.

As Mercer came to see the clearly underhanded treatment of individual ranchers by the cartels, he began to write more scathing accounts of the events that were unfolding on the open range.

Following the events of the Johnson County War, which included destruction of his newspaper office by arson, Mercer settled into the quiet life of a rancher in Hyattville, Wyoming.