In 1874, the Spear family migrated by wagon train to Evanston, Wyoming. Willis Spear eventually settled in Big Horn, Wyoming in 1883.
Spear and his brother formed the Spear Brothers Cattle Company in 1896. Every year from 1899 to 1914, he went on cattle-buying trips to Texas and Mexico. The company acquired five ranches along the Powder River and leased an additional 1,000,000 acres on the Crow Indian Reservation. They ranged from 32,000 head of their own stock and 26,000 head for other companies.
Spear installed the first rural telephone lines in the state to help manage the operation.
From 1918 to 1932, he served as a senator in the Wyoming State Legislature.
