[1] A newspaper publisher by trade, Brown was a Democrat who served as Clerk and Recorder of Iowa County, Wisconsin, and was a member of the first board of regents of the University of Wisconsin–Madison.

He was the roommate of Horace Greeley, his political opposite who later became a noted newspaper editor in New York City.

[2][3] As the editor of the daily Democratic Press in San Francisco, he amassed a large library; when news arrived of the assassination of Abraham Lincoln, a mob ransacked Brown's office and burned 20,000 volumes.

[3] He supported the establishment of a white supremacist colony in Sonora, Mexico, and opposed the Civil War.

On July 8, 1878, Brown was elected mayor of Seattle as a People's Ticket candidate.