[5] According to the United States Census Bureau, the city has a total area of 3.1 square miles (8.0 km2), all land.

The climate in this area is characterized by hot, humid summers and generally mild to cool winters.

[6] As of the 2020 United States census, there were 5,323 people, 2,026 households, and 1,154 families residing in the city.

Rockdale was the site of a large Alcoa aluminium smelting facility, which could produce 1.67 million pounds of aluminum per day.

[11] The Alcoa plant profoundly changed the city, as noted in a Saturday Evening Post article by Rockdale native George Sessions Perry.

Within a few years of its arrival in 1952, Rockdale almost doubled in population, changing in character from a predominantly agricultural economy to one heavily driven by manufacturing jobs.

[15][16] Two cryptocurrency miners, Bitdeer, a division of Bitmain, and Riot Blockchain, formerly known as Bioptix, occupy former Alcoa facilities less than half a mile apart in Rockdale, using electricity transmission lines built to connect smelters to the power plant.