[5] In 1968, he also began a career as a cattleman and rancher when he started Brewster Angus Farms, as well as owning a real estate business.

[8] In the 1990 elections, Brewster ran for an open seat in the U.S. House of Representatives (District 3—then Congressman Wes Watkins had decided to retire from Congress and run for Governor of Oklahoma).

Brewster won the heavily contested Democratic nomination against Lieutenant Governor Robert S. Kerr III.

[16] Brewster married Mary Sue "Suzie" Nelson in 1963, and the couple had three children: Balynda Karel, Betsy Kecia, and Bradley Kent.

On January 31, 1990, Betsy Kecia and Bradley Kent died in a plane crash with friends of the family.