The area known as Killen in Lauderdale County, was settled in the early 1800s. In 1826, Joseph Mason was appointed the first postmaster of the new community called Masonville, later to become Killen. The post office existed until 1866. In the 1830s the construction of the Alabama Canal brought growth to the area. The canal was built to solve the navigation problems created by the shoals in the Tennessee River. Construction on the new canal began in 1875 and the 14 1/2 - mile canal, with nine locks with a lift of 85 feet, opened November 10, 1890. The canal was renamed the Muscle Shoals Canal. Lock six served as the headquarters and was located just 1/2- mile south of Killen. The canal system had a major economic impact on the development of Killen. Many of the citizens were employed on the canal and others supplied raw materials and food for the operation.
In 1885, 200 men were employed by the Corps of Engineers. Many of these men built homes near their work. In 1895, Mr. James Sharp Killen built a general store and applied for a post office. He sent in three possible names with the application and Killen was chosen. The post office opened on August 22, 1896 and the Town of Killen was founded. Killen was incorporated and established a police department in 1957. A fire department was started in 1962 and a town park was added in 1976. The town library was established in 1985. Killen has grown because of the good citizens of this community and the moral fortitude established by our local churches. The Killen Lions Club was chartered in 1957 and is a major community asset. Other sources of pride for the Killen area are Brooks Elementary, dating to 1908, and Brooks High School which opened in 1968.