Housing is a representation of the maximum amount of Citizens or Population you can have in each city. The base source of Housing is a water source.

Many buildings grant Housing. After researching Pottery, every city is able to build a Granary, which adds 2 Housing, and later they can build Sewers, which also adds 2 Housing. Buildings in other districts sometimes add Housing, such as the Barracks in the Encampment district, the University in the Campus, and the Lighthouse in the Harbor. The Palace building in your capital city also adds 1 Housing.

Each Farm, Pasture, Plantation, or Camp supports a small amount of Population — 1 Housing for every 2 such improvements. Supporting rural Population in this fashion will allow for slightly larger Populations prior to the Industrial Era, when the Neighborhood district becomes available.