Ferry served as director and vice-president of the Utah Savings & Trust Co, the director of the Walker Brothers Bank, the Silver King Coalition Mines, and the Mason Valley Mines of Nevada.

[1] In January 1903, Thompson was a signatory of an official protest to the United States Senate of the Utah Legislature's election of Mormon apostle Reed Smoot as a United States Senator for Utah.

In 1904, when Kearns failed to be re-elected to the Senate by the Utah Legislature due to the perceived influence of Smoot, Ferry was among the founders of the anti-Mormon American Party.

In 1911, the American Party dissolved, and Ferry was elected as a Republican to the Utah State Senate.

He served in the State Senate until 1915, when he was elected mayor of Salt Lake City.