They moved to Wisconsin in 1884 and finally to Helena, Montana, in 1885. Cooper passed the bar examination in 1892,[1] and entered the practice of law in the state.
In 1906, Cooper purchased the 600-acre (240 ha) Seven-Bar-Nine cattle ranch,[3][4] about 50 miles (80 km) north of Helena near Craig, Montana.
[1] Cooper married Alice Louise Brazier of Gillingham, England, on March 24, 1894, with whom he had two sons,[1] Arthur and Frank.
After he retired from the Supreme Court in 1924, Cooper and his wife moved to California to manage several estates left to him in a will.
During World War II, Cooper often read Shakespeare to hospitalized soldiers.