At the age of 23, he moved to Little Rock in 1838. After arriving, he soon became the editor and publisher of the Times and Advocate newspaper. As a publisher and printer, Colby also had the contract to print official state notifications and documents in the early 1840s.
Politically, Colby served as a Justice of the Peace for several years. In September 1843, he was elected Mayor of Little Rock in a special election to fill a vacancy. He left office in January 1844. He died March 15, 1844, at the age of 29 after a long illness and was buried with Masonic honors.