[4] Hillsboro began in the late 1830s as a small community known as "Gilmersville," which was located east of the current town.

When the railroad was constructed through the area in the 1860s, the town shifted to its current location along the tracks.

The town developed throughout the latter half of the 19th century as an important refueling stop for trains and a local shipping center.

[5] The town is concentrated along County Road 217 (Main Street) just south of the road's railroad crossing, a few miles west of Decatur, and a few miles south of Wheeler Lake.

According to the U.S. Census Bureau, the town has a total area of 1.9 square miles (4.9 km2), all land.

As of the 2020 United States census, there were 407 people, 215 households, and 143 families residing in the city.