Bynum is thirty miles north of Waco and eight miles southeast of Hillsboro on State Highway 171 in east central Hill County. The town was named for a pioneer settler. At the site was an ancient Indian burial ground. In 1882 Judge J. P. Connell built a small establishment with a "stock of goods" and opened a post office that was named Hanover and operated until 1884. Ranches and, to the north, farms surrounded the establishment. Due to a lack of business the store closed by 1884. Henry M. Mucklevane opened a general store about 1890, and a post office called Bynum began operation in 1886 in the same vicinity as the original store. In 1896 the town had a population of 150, a district school, Baptist and Christian churches, a music teacher, a blacksmith, a grocer, the Bynum String Band, a barber, a druggist, a general store, and two doctors.
The town moved a half mile to its present location when the Texas and Brazos Valley Railroad arrived in 1904. The community purchased the farm of W. W. Cabell for its new townsite. In March, town lots were sold. J. C. Barnard's grocery, Dr. Saylor's drugstore, and the privately owned Bank of Bynum were housed in brick buildings. The population was 163. The Baptist, Methodist, and Christian churches were moved from the old townsite. In 1905 the Bynum Independent School District was organized, and residents voted on a bond for the construction of a two-story brick school building for $5,000. Professor T. W. Swofford was hired as the teacher and assisted by older students.
A fire destroyed most of the business district in 1925, but it was rebuilt the same year. By 1926 Bynum had a population of 350, which it maintained until 1964. A tornado destroyed much of the downtown area in 1930. Nevertheless, the town supported twenty businesses in 1931, though half of them closed the following year. The Great Depression and the boll weevil plague were mainly responsible for the shrinkage. People along the T&BV railroad called it the "Boll Weevil" route. The railroad was sold to the Burlington-Rock Island in 1930, and in an effort to reduce its losses the B-RI closed the track between Hillsboro and Hubbard in 1935. State Highway 171 connecting Hillsboro and Mexia was built at that time.
Bynum did not recover until 1949, when the number of businesses reached eighteen and the Gilmer-Aikin Laws forced the consolidation of smaller school districts. Schools in Brandon, Prairie Valley, Davis, Irene, Malone, Watson, and Grove Creek were added to the Bynum system. By 1956 the number of businesses began to decline again. Henry Markwardt's grocery store served the town in the 1960s, but by the 1980s no businesses were reported and the bank had been moved to Hillsboro. The population of Bynum was 130 in 1972 and 192 in 1990. In 2000 the community had six businesses and 225 inhabitants.