Mercury is on Farm Road 502 twenty-two miles northeast of Brady in northeastern McCulloch County. It was founded by J. A. Austin in 1904, soon after the Fort Worth and Rio Grande built through the area. Mercury became a shipping point for livestock. In 1914 the town had two banks, two general stores, and 550 residents. Mercury had two disastrous fires, one in 1919 and one in 1929, and was unable to recover from them. The town was bypassed when the Brownwood-Brady highway was rerouted in 1938. The Mercury post office was discontinued in the 1930s, and the community's population declined steadily over the next several decades. The Mercury schools were consolidated with the Rochelle district in the late 1940s. The community's population fell from 489 in 1933 to 360 in 1949; it reported 166 residents in 1988 through 2000.