First off, Civ-Revolution is the first Civ game I've played so pardon my ignorance. When I was playing earlier I noticed that with my large city, almost none of the squares around were being "used". For example, I could have a city, let's call it Dijon, with a population of 20 and a courthouse. Dijon's working squares extend out 3 spaces in every direction, with a great mix of resources (food, production, trade). I'm not at war with anyone and there are no units or towns in the area. Let's also assume that I have the workshop so that hills are worth 3 production. Now let's say that only 3 or 4 of the working squares are being utilized, mostly for food.
Maybe I'm not looking at this closely enough. Why would one of the population stay in the city to produce 1 production or 1 production and 1 trade vs going to a hill to make 3?