Building a Worker: A city that builds a worker loses one citizen from its population. Worker Jobs: Workers can improve the countryside to make it more productive. The efficiency of a worker (how quickly it works) depends upon its government type. Joining a City: A worker may also be used to increase the population of an existing city; when the worker is active on a city, click the "Join City" button. The worker disappears and the city's population gains one citizen. Note that workers may be captured and used by rival civilizations.