The settlement of Harrison County began around 1838, although the land was not surveyed and opened for entry until 1842. The county is named after Albert C Harrison who was a Missouri politician during the 19th century. Many of the early pioneers in the county settled along Sugar Creek and in the Bethany area. Three commissioners deliberated for several days to determine a site for the county seat and finally came to the decision to place it in the southern part of the county. The original name for the community was Dallas.
In June of 1845, John S. Allen was appointed commissioner to survey the town into lots and offer the same for sale. The plat which was completed on June 27, 1845 consisted of 19 total acres.
The name Dallas apparently did not meet with the general approval of the residents of the community and the issue was brought before the county court. It was decided that the court and county officials present would select a new name by ballot. The names of Bethany and Carthage were proposed. The Votes showed a majority favored the name of Bethany and accordingly the name of Bethany was given to the town. It was officially incorporated as a city by an act of the General Assembly on January 6, 1860. The first mayor was T.H. Templeman.
The first home constructed in the community was built by John S. Allen and although it was built as a residence it was primarily used to store the first stock of goods brought to the community. Like many original landmarks it was completely destroyed by fire in 1864.
The Chicago, Burlington and Quincy railroad reached Bethany in October 1890. Eventually, two other railroads also served the county. The railroad would influence the economy and environment of the community for the next century until in the early 1980's when the last train pulled out of the Bethany Depot and the tracks were removed permanently. Transportation was an important industry to the community and the population grew to its greatest level around the turn of the century when over 24,000 persons lived in Harrison County.
Industry played a vital role in Bethany's growth starting with Colonel C.L. Jennings who erected the first steam mill around 1854 in the northwest part of town. This was a combination mill which produced both lumber and flour. Because the country was so new, little need for towns existed. For several years, only a few retail shops existed and development and growth of the town was slow but by 1855, Bethany was known as one of the best trading places in Northwest Missouri. An industrial park was established in the 1960's by the Harrison County Industrial Development Authority and the Bethany Memorial Airport was opened in 1968. The first tenant in the industrial park was Calhoun Manufacturing, a company which manufactured agriculture machinery. Lambert Manufacturing opened a facility in 1971 and Place's Discount Stores also became a resident of the industrial park until 1999 when they sold to Pamida, with the distribution center remaining active with-in the park until 2002 when it closed. The 120,000 square foot building was purchased by the home grown Bethany business Gumdrop Books immediately following Pamida's closure. Newest additions to the park include Superior Waste, and Tri-State Carports which opened for business in 2001. The 1990's seen period of aggressive growth, especially within the service industry with the addition of several motels and restaurants. There has been several million dollars investment each year during the 90's and an increase of nearly 100 jobs annually.
Through the years, development continued and included the construction of a lake in 1935 to serve the water needs of the community. In 1960, a second lake was added so that Bethany could meet the increasing water needs. The Harrison County Lake was completed in 1994 and provides a third source of water for the community. In 1954, residents voted to issue bonds to build a municipal swimming pool. Numerous other utilities were upgraded from 1930 to 1970 including the construction of a water tower in 1989 to serve growth along the north side of tow. In 1996, residents approved a sales tax to extend water lines from the new tower to the south side of town which resulted in a looping of the system and improved water pressure for many areas of town. The sales tax also funded the reconstruction of Main Street from Highway 69 to the square.
Transportation, which played an important role early in Bethany's history, came to play an even bigger role in the 1960's when Interstate 35 was proposed and later constructed. This north-south 4-lane highway connects Canada with Mexico. The interstate ran along the east side of town and since the completion of the interstate in the early 1970's, the communities growth has been in that direction with a number of retail establishments appearing in the 1980's and that growth continues today.